The Daily Galaxy --Great Discoveries Channel: Sci, Space, Tech

"Cosmic Evolution Tends to Extinguish Species that Advertise Themselves" --The Dangers of Messaging ET

2013-06-19T07:42:55-07:00

“Evolutionary selection, acting on a cosmic scale, tends to extinguish species which conspicuously advertise themselves and their habitats,” according to Adrian Kent, Centre for Quantum Computation, University of Cambridge.

Science fiction writer and astrophysicist Dr. David Brin echoed Kent's thesis with his reponse to the recent Lone Signal announcement of METI (Messaging to Extra-Terrestrial Intelligence) “beams” to the Gliese 526 solar system.

In his Brinstorming Science 2.0 blog, Brin updated his 2006 article on METI (aka active SETI), writing: "Recently, several groups, ranging from radio astronomers in Argentina and Russia all the way to the web advertising site Craigslist, have declared that they intend to commence broadcasting high-intensity Messages to ETI... or METI... an endeavor also known at "Active Seti." Their intention is to change the observable brightness of Earth civilization by many orders of magnitude, in order to attract attention to our planet from anyone who might be out there."

Specifically, Brin is responding to the "Lone Signal" project that believes that crowd sourcing messaging to intelligent life (METI) is the ideal approach to establishing a stable, cohesive, and well-resourced interstellar beacon on Earth. Anyone with Internet access to compose and transmit messages to strategically targeted stellar systems. Launching June 18, 2013, Lone Signal’s unfettered access to the broadcasting capacity of Jamesburg Earth Station in Carmel, CA allows them to target the closest known stars suspected to harbor potentially habitable planets orbiting in their circumstellar habitable zones — otherwise referred to as “Goldilocks zones.”

Through their website, users are given the opportunity to upload and transmit content to these targets (e.g., texts, images, and, ultimately, audio and video). Lone Signal is the first continuous, collective, and cohesive METI experiment of its kind.

Comparing the magnitude of deliberate radio broadcasts intended for messaging to extraterrestrial intelligence (METI) with the background radio spectrum of Earth, METI attempts to date have much lower detectability than emissions from current radio communication technologies on Earth.

METI broadcasts are usually transient and several orders of magnitude less powerful than other terrestrial sources such as astronomical and military radars, which provide the strongest detectable signals.

If we should pick up signals from alien civilizations, Stephen Hawking, our century's Einstein, warns: "we should have be wary of answering back, until we have evolved" a bit further. Meeting a more advanced civilization, at our present stage,' Hawking says "might be a bit like the original inhabitants of America meeting Columbus. I don't think they were better off for it."

Earth's attempts to contact intelligent, extraterrestrial life could be too disorganised or cryptic for non-human beings to decode, many physicists have reported. In a submission to the international journal, Space Policy, astrophysicists Dimitra Atri, Julia DeMarines and Jacob Haqq-Misra suggested that a protocol be developed to improve the likelihood that messages would be understood.

Let there be no mistake, Brin says, "METI is a very different thing than passively sifting for signals from the outer space. Carl Sagan, one of the greatest SETI supporters and a deep believer in the notion of altruistic alien civilizations, called such a move deeply unwise and immature. (Even Frank Drake, who famously sent the "Arecibo Message" toward the Andromeda Galaxy in 1974, considered "Active Seti to be, at best, a stunt and generally a waste of time.) Sagan -- along with early SETI pioneer Philip Morrison -- recommended that the newest children in a strange and uncertain cosmos should listen quietly for a long time, patiently learning about the universe and comparing notes, before shouting into an unknown jungle that we do not understand.

"In The Third Chimpanzee, Jared Diamond offers an essay on the risks of attempting to contact ETIs, based on the history of what happened on Earth whenever more advanced civilizations encountered less advanced ones... or indeed, when the same thing happens during contact between species that evolved in differeing ecosystems. The results are often not good: in inter-human relations slavery, colonialism, etc. Among contacting species: extinction."

Dr Alexander Zaitzev, of the Institute of Radio Engineering and Electronics at the Russian Academy of Sciences, doesn't think much of these worries either way. A proponent of METI (Messaging to Extra-Terrestrial Intelligence), in a paper he shows that the odds of one of the METI messages being detected is a millionth of that due to powerful radar pulses regularly used in astronomical investigation. Though whether writing a paper saying "This METI thing we're doing has only a tiny chance of working" is overall a good idea remains to be seen. An important point is that METI represents an intentional will to make contact, rather than the accidental alien interception of some random radiation from Earth - the difference between saying "Hello!" and just being a suspicious strange noise late at night.

“Intelligent species might reasonably worry about the possible dangers of self-advertisement and hence incline towards discretion” -- the “Undetectability Conjecture,” put forth by Beatriz Gato-Rivera, a theoretical physicist at the Instituto de Fisica Fundamental (previously Instituto de Matematicas y Fisica Fundamental) of the CSIC (Spanish Scientific Research Council) in Madrid.
According to Gato-Rivera, we may find ourselves in a universe in which there exist intelligent technological civilizations but they have chosen to be undetectable, camouflaging themselves mainly for security reasons (because advanced civilizations could also be aggressive).

The Daily Galaxy via Lone Signal and http://www.rationalvedanta.net/node/131 and http://www.science20.com/brinstorming/meti_should_we_be_shouting_cosmos-114283

Image of the Day: Brilliant Supernova 12 hours After it Exploded in the Pinwheel Galaxy

2013-06-19T04:00:00-07:00

August, 2011, saw the dazzling appearance of the closest and brightest Type Ia supernova since Type Ia's were established as "standard candles" for measuring the expansion of the universe. The brilliant visitor, labeled SN 2011fe, was caught by the Palomar Transient Factory less than 12 hours after it exploded in the Pinwheel Galaxy in the Big Dipper. Easy to see through binoculars, 2011fe was soon dubbed the Backyard Supernova. Major astronomical studies from the ground and from space followed close on its heels, recording its luminosity and colors as it rapidly brightened and then slowly faded away.

The international Nearby Supernova Factory (SNfactory), led by Greg Aldering of the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab), has now released a unique dataset based on 32 nights of repeated observations of 2011fe with the SuperNova Integral Field Spectrograph (SNIFS), built by the SNfactory's partners in Lyon and Paris, France, and mounted on the University of Hawaii's 2.2-meter telescope on Mauna Kea. The observations began two weeks before the supernova reached its peak brightness and continued for over three months after maximum light had passed.

"We'd never before seen a Type Ia supernova this early," says Aldering, a cosmologist in Berkeley Lab's Physics Division. "Our measurements showed how remarkably normal 2011fe is."

SNfactory member Rui Pereira of the Institut de Physique Nucléaire de Lyon says that the collected data "will be benchmark atlas for all future studies of Type Ia's." Pereira is the lead author of the article presenting the observations in the journal Astronomy & Astrophysics.

Type Ia supernovae aren't so much standard candles as "standardizable" ones. Graphs of how their brightness and spectral features change over time – their light curves – vary, but because timing and brightness are related, the light curves can be stretched (or squeezed) to match the standard. SN 2011fe's light curve falls right in the peak of the distribution – as astrophysicists say, it has "stretch 1."

Rollin Thomas, of Berkeley Lab's Computational Research Division, was deeply involved in the 2011fe analysis. As new data arrived from the telescope each night he recalls thinking "please don't be peculiar, please don't be peculiar," and was pleased to find that the supernova was so normal.

2011fe not only looks like a textbook case, it passes important tests. Its brightness at different times (epochs) could be accurately recorded because the distance to its home galaxy had been measured independently, and there was little or no dust in the line of sight to affect color or brightness.

Normal as it is, however, 2011fe's light curve doesn't match the leading computational models, none of which fit the SNfactory data. Given the unavoidable uncertainties of supernova observation, says Aldering, "to date it has been a little too easy to cobble data together, depending on what you think it should be." The SNfactory's benchmark atlas raises the bar. "From now on researchers won't be able to arbitrarily tweak knobs in their models."

The 2011fe gold-standard atlas will help answer many longstanding questions about Type Ia supernovae, including the progenitors of these titanic thermonuclear explosions and the mechanisms of the explosions themselves.

The single degenerate model of Type Ia progenitors posits a single white dwarf that steals extra mass from a large companion star. (Electron "degeneracy" is a result of tight packing of atoms in a white dwarf.) In the resulting supernova explosion there should be signs of interaction with the companion, or what's left of it. In the double degenerate model, two white dwarfs collide. The resulting supernova would show no signs of interaction with a companion.

"The 2011fe observations can be used to test these models," says Aldering. "For 2011fe, the existing models of the double-degenerate scenario agreed best at some epochs, but the single-degenerate scenario was better at others. And for some epochs both agreed very poorly with the data, suggesting these models have a way to go."

The 2011fe data also point to unburned carbon as characteristic of the spectrum of a normal Type Ia. The finding adds support for a particular model, "pure turbulent deflagration," compared to two-stage explosions that would eliminate most excess carbon.

Carbon surviving from the original white dwarf indicates that different supernovae burn material with a range of different efficiencies when they explode. Methods for detecting unburned carbon, which may often have been missed in the past, are suggested by the 2011fe data.

In sum, says Aldering, "The SN 2011fe atlas offers unprecedented detail and a solid point of reference for Type Ia physics. We've never had data like this. It's a dream opportunity to stimulate deeper thinking about these markers of the expansion of the universe."

The Daily Galaxy via lbl.gov

Billion-Pixel View of Mount Sharp --Mars' Curiosity Rover Destination

2013-06-19T01:42:00-07:00

This full-circle view combined nearly 900 images taken by NASA's Curiosity Mars rover, generating a panorama with 1.3 billion pixels in the full-resolution version. The view is centered toward the south, with north at both ends. It shows Curiosity at the "Rocknest" site where the rover scooped up samples of windblown dust and sand. Curiosity used three cameras to take the component images on several different days between Oct. 5 and Nov. 16, 2012.

This first NASA-produced gigapixel image from the surface of Mars is a mosaic using 850 frames from the telephoto camera of Curiosity's Mast Camera instrument, supplemented with 21 frames from the Mastcam's wider-angle camera and 25 black-and-white frames -- mostly of the rover itself -- from the Navigation Camera. It was produced by the Multiple-Mission Image Processing Laboratory at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

This version of the panorama retains "raw" color, as seen by the camera on Mars under Mars lighting conditions. A white-balanced version is available at http://photojournal.jpl.nasa.gov/catalog/PIA16918 . The view shows illumination effects from variations in the time of day for pieces of the mosaic. It also shows variations in the clarity of the atmosphere due to variable dustiness during the month while the images were acquired.

Viewers can explore this image with pan and zoom controls at http://mars.nasa.gov/bp1/ .

NASA's Mars Science Laboratory project is using Curiosity and the rover's 10 science instruments to investigate the environmental history within Gale Crater, a location where the project has found that conditions were long ago favorable for microbial life.

Malin Space Science Systems, San Diego, built and operates Curiosity's Mastcam. JPL, a division of the California Institute of Technology, Pasadena, manages the Mars Science Laboratory project for NASA's Science Mission Directorate in Washington and built the Navigation Camera and the rover.

Credit: NASA/JPL-Caltech/MSSS

"Planets Billions of Years Older Than Earth May Exist in the Milky Way" (Featured Post)

2013-06-19T01:02:00-07:00

Building a terrestrial planet requires raw materials that weren't available in the early history of the universe. The Big Bang filled space with hydrogen and helium. Chemical elements like silicon and oxygen - key components of rocks - had to be cooked up over time by stars. But how long did that take? How many of such heavy elements do you need to form planets?

Studies have shown that Jupiter-sized gas giants tend to form around stars containing more heavy elements than the Sun. However, research by a team of astronomers completed last year found that planets smaller than Neptune are located around a wide variety of stars, including those with fewer heavy elements than the Sun. As a result, rocky worlds like Earth could have formed earlier than expected in the universe's history.

"This work suggests that terrestrial worlds could form at almost any time in our galaxy's history," said Smithsonian astronomer David Latham (Harvard-Smithsonian Center for Astrophysics). "You don't need many earlier generations of stars." Latham played a lead role in the study, which was led by Lars A. Buchhave from the University of Copenhagen published in the journal Nature.

Astronomers call chemical elements heavier than hydrogen and helium "metals." They measure the metal content, or metallicities, of other stars using the Sun as a benchmark. Stars with more heavy elements are considered metal-rich while stars with fewer heavy elements are considered metal-poor.

Latham and his colleagues examined more than 150 stars known to have planets, based on data from NASA's Kepler spacecraft. They measured the stars' metallicities and correlated that with the sizes of the associated planets. Large planets tended to orbit stars with solar metallicities or higher. Smaller worlds, though, were found around metal-rich and metal-poor stars alike.* "Giant planets prefer metal-rich stars. Little ones don't," explained Latham.

They found that terrestrial planets form at a wide range of metallicities, including systems with only one-quarter of the Sun's metal content.

Their discovery supports the "core accretion" model of planet formation. In this model, primordial dust accumulates into mile-sized planetesimals that then coalesce into full-fledged planets. The largest, weighing 10 times Earth, can then gather surrounding hydrogen and become a gas giant.

A gas giant's core must form quickly since hydrogen in the protoplanetary disk dissipates rapidly, swept away by stellar winds in just a few million years. Higher metallicities might support the formation of large cores, explaining why we're more likely to find a gas giant orbiting a metal-rich star."This result fits with the core accretion model of planet formation in a natural way," said Latham.

The Daily Galaxy via Harvard-Smithsonian Center for Astrophysics

Galaxy Starbursts Triggered by Dark Matter --A Herschel Space Observatory Discovery

2013-06-18T07:38:15-07:00

Most of the mass of any galaxy is expected to be "dark matter," the elusive X Factor that has yet to be detected but which astronomers believe must exist to provide sufficient gravity to prevent galaxies ripping themselves apart as they rotate. But ESA’s Herschel space observatory has discovered a population of dust-enshrouded galaxies that do not need as much "dark matter" as previously thought to collect gas and burst into star formation.

With the end of Europe's Herschel Space Telescope (ground controllers put the Herschel Observatory in sleep mode yesterday), turning off the infrared observatory, we thought it would be appropriate to feature one of the observatory's great accomplishments.

“Herschel is showed us that we don’t need quite so much dark matter as we thought to trigger a starburst,” says Asantha Cooray, University of California, Irvine. Current models of the birth of galaxies start with the accumulation of large amounts of dark matter believed to reside in a considerably larger assembly, or halo. Its gravitational attraction drags in ordinary atoms. If enough atoms accumulate, a ‘starburst’ is ignited, in which stars form at rates 100–1000 times faster than in our own galaxy does today.

Dark matter halos are, according to the most commonly accepted theory for the formation of cosmic structure, the sites where galaxies take shape. In this theory, tiny fluctuations in the early Universe grew, under the attractive effect of gravity, into a complex network of dark matter sheets and filaments - the so-called cosmic web; later, gas accumulating in the densest knots of the cosmic web began to cool, giving rise to clumps where the first stars formed and which would later assemble into galaxies.

Since the cosmic web constitutes the skeleton supporting the later emergence of stars and galaxies, the distribution of galaxies is expected to follow, and thus trace, that of the dark matter. Whereas the growth of dark matter structures is only regulated by gravity, a number of additional phenomena affect star and galaxy formation, resulting in two different clustering trends. Astronomers refer to this by saying that galaxies are biased tracers of the dark matter distribution.

An interesting feature in this context is that all galaxies are to be found within dark matter halos, with one or more galaxies inhabiting a halo, but not all halos are expected to harbour a galaxy.

"The formation of a galaxy is simply not efficient enough in halos with masses that are either too large or too small," explains Asantha Cooray from the University of California, Irvine, USA, who directed the study based on Herschel data that has revealed new details about the most efficient sites for galaxy formation.

This dark matter discovery was made by analyzing infrared images taken by Herschel’s SPIRE (Spectral and Photometric Imaging Receiver) instrument at wavelengths of 250, 350, and 500 microns. These are roughly 1000 times longer than the wavelengths visible to the human eye and reveal galaxies that are deeply enshrouded in a fog of dust.

“With its very high sensitivity to the far-infrared light emitted by these young, enshrouded starburst galaxies, Herschel allows us to peer deep into the Universe and to understand how galaxies form and evolve,” says Göran Pilbratt, the ESA Herschel project scientist.
The team of astronomers used HerMES observations of two fields, the Lockman Hole (see below) and the GOODS North. "With its large telescope and its unprecedented resolution and sensitivity at these far-infrared wavelengths, Herschel is a unique facility that has now made it possible to scrutinize the CIB fluctuations down to scales that reveal really interesting information about the emergence of starburst galaxies around the peak of the star formation history of the Universe," comments Goran Pilbratt, Herschel Project Scientist at ESA.

The galaxies in the Hershel images are not distributed randomly but follow the underlying pattern of dark matter in the Universe, and so the fog has a distinctive pattern of light and dark patches.

Analysis of the brightness of the patches in the SPIRE images has shown that the star-formation rate in the distant infrared galaxies is 3–5 times higher than previously inferred from visible-wavelength observations of similar, very young galaxies by the Hubble Space Telescope and other telescopes.

Further analysis and simulations have shown that this smaller mass for the galaxies is a sweet spot for star formation. Less massive galaxies find it hard to form more than a first generation of stars before fizzling out. At the other end of the scale, more massive galaxies struggle because their gas cools rather slowly, preventing it from collapsing down to the high densities needed to ignite star formation.

But at this newly identified ‘just-right’ mass of a few hundred billion solar masses, galaxies can make stars at prodigious rates and thus grow rapidly.

“This is the first direct observation of the preferred mass scale for igniting a starburst,” says Dr Cooray.

The image below shows the patch of the sky known as the 'Lockman Hole', as observed by the SPIRE instrument on board Herschel. Located in northern constellation of Ursa Major, The Great Bear, the 'Lockman Hole' is a field on the sky almost devoid of foreground contamination and thus ideally suited for observations of galaxies in the distant Universe.

Almost every dot in the image is an entire galaxy, each containing billions of stars and appearing as they did 10-12 billion years ago, when the Universe was only a couple of billion years old. The blue, green and red colours represent the three far-infrared wavelengths used for Herschel's observations: 250, 350 and 500 micron, respectively.

The galaxies shown below in white have equal intensity in all three wavebands and are the ones forming the most stars. Detecting these galaxies individually is particularly challenging, as they are both extremely faint and numerous, so many of them overlap in Herschel's images. This creates a fog of infrared radiation known as the Cosmic Infrared Background (CIB), which reflects the clustering pattern of the galaxies responsible for this fog. Studying the CIB and its fluctuations is thus an extremely powerful tool to explore the way galaxies tend to be grouped on both small and large scales.

Models of galaxy formation can now be adjusted to reflect these new results, and astronomers can take a step closer to understanding how galaxies – including our own –came into being.

The image at the top of the page shows dwarf galaxy NGC 1569 undergoing a burst of star forming activity, thought to have begun over 25 million years ago. The resulting turbulent environment is fed by supernova explosions as the cosmic detonations spew out material and trigger further star formation. Two massive star clusters - youthful counterparts to globular star clusters in our own spiral Milky Way galaxy - are seen left of center in the gorgeous Hubble Space Telescope image. The above picture spans about 8,000 light-years across NGC 1569. A mere 11 million light-years distant, this relatively close starburst galaxy offers astronomers an excellent opportunity to study stellar populations in rapidly evolving galaxies.

The Daily Galaxy via ESA and APOD

"Earth Calling" --A 'YouTube' for Messaging Advanced Extraterrestrial Life

2013-06-18T06:45:00-07:00

A new project aclled "Lone Signal" believes that crowd sourcing messaging to intelligent life (METI) is the ideal approach to establishing a stable, cohesive, and well-resourced interstellar beacon on Earth. Anyone with Internet access to compose and transmit messages to strategically targeted stellar systems. Launching June 18, 2013, Lone Signal’s unfettered access to the broadcasting capacity of Jamesburg Earth Station in Carmel, CA allows them to target the closest known stars suspected to harbor potentially habitable planets orbiting in their circumstellar habitable zones — otherwise referred to as “Goldilocks zones.”

There has been some serious controversy over prior attempts to contact intelligent aliens, where instead of hiding in the corner and listening real hard some astronomers have beamed intense directional messages up up and away. Critics decried these actions as dangerous, though their fears reveal more about us than any eventual ETs. They assume that they would be similar to humanity, so their first response to finding a more primitive culture would be to exploit it. While such a fate might be pleasingly ironic (for anyone who isn't human, at least), others contend that any species that can make the journey here has advanced to a point where their goals are rather higher-minded than "Destroy Planet Earth".

Most of the objections to contacting aliens are weak under close examination. We can't suddenly decide to hide after fifty years of pumping electromagnetic radiation into space without rhyme or reason - in fact, we'd better hope that an advanced civilization doesn't catch an episode of "American Idol" and just vaporize us outright.

Then there's the assumption that aliens would have the same kind of technology we do - despite the extremely obvious fact that our technology can't actually get to other exo planets. Any attempt to mask radio emissions will likely look like cavemen closing their eyes to hide from satellite imaging.

Undaunted by prior controversy swirling around the METI effort, Atri and his team argued that Earth had been emitting electromagnetic signals for more than a century, mostly as "unintended leakage from television, aviation, and telecommunication".

"An advanced civilization within a radius of 100 light years could detect our television shows and already know we are here, so there is little hope in concealing our location in space," they wrote.

Since 1974, humans have broadcast the numbers one through ten, atomic numbers of elements in DNA, graphics of a human, the solar system, and Arecibo, musical melodies, text messages, photographs and drawings.

The researchers believe that messages had become increasingly "anthropocentric" and complex, which could make them more difficult for extraterrestrial listeners to decode and decipher.

"Modern technology allows for large amounts of data to be transmitted at moderate costs, but the broadcast of massive amounts of information assumes that the recipient extraterrestrials will be capable of comprehending a complex message," they wrote.

"Given that we know very little about the nature of extraterrestrial civilizations, if they exist, we are likely to increase the probability of us successfully communicating to them if we use a message that the recipient is likely to understand."

Once developed, a METI protocol could be used to test communication across human cultural boundaries, the researchers wrote.

They suggested the establishment of a website through which members of the public could create sample messages that conformed to the protocol, and retrieve and attempt to decrypt messages by other users.

"A METI protocol is needed in order for a unified and international effort to be made in messaging extraterrestrials," they concluded.

The Daily Galaxy via Lone Signal and http://www.rationalvedanta.net/node/131

"The Great Attractor" --Is Something is Pulling Our Region of the Universe Towards a Colossal Unseen Mass?

2013-06-18T05:00:00-07:00

A busy patch of space has been captured in the image below from the NASA/ESA Hubble Space Telescope. Scattered with many nearby stars, the field also has numerous galaxies in the background. Located on the border of Triangulum Australe (The Southern Triangle) and Norma (The Carpenter’s Square), this field covers part of the Norma Cluster (Abell 3627) as well as a dense area of our own galaxy, the Milky Way.

The Norma Cluster is the closest massive galaxy cluster to the Milky Way, and lies about 220 million light-years away. The enormous mass concentrated here, and the consequent gravitational attraction, mean that this region of space is known to astronomers as the Great Attractor, and it dominates our region of the Universe.

he largest galaxy visible in this image is ESO 137-002, a spiral galaxy seen edge on. In this image from Hubble, we see large regions of dust across the galaxy’s bulge. What we do not see here is the tail of glowing X-rays that has been observed extending out of the galaxy — but which is invisible to an optical telescope like Hubble.

Observing the Great Attractor is difficult at optical wavelengths. The plane of the Milky Way — responsible for the numerous bright stars in this image — both outshines (with stars) and obscures (with dust) many of the objects behind it. There are some tricks for seeing through this — infrared or radio observations, for instance — but the region behind the center of the Milky Way, where the dust is thickest, remains an almost complete mystery to astronomers.

Recent evidence from the European Space Agency's Atacama Desert telescopes in Chile appears to contradict the "great attractor" theory. Astronomers have theorized for years that something unknown appears to be pulling our Milky Way and tens of thousands of other galaxies toward itself at a breakneck 22 million kilometers (14 million miles) per hour. But they couldn’t pinpoint exactly what, or where it is.

A huge volume of space that includes the Milky Way and super-clusters of galaxies is flowing towards a mysterious, gigantic unseen mass named mass astronomers have dubbed "The Great Attractor," some 250 million light years from our Solar System.

The Milky Way and Andromeda galaxies are the dominant structures in a galaxy cluster called the Local Group which is, in turn, an outlying member of the Virgo supercluster. Andromeda--about 2.2 million light-years from the Milky Way--is speeding toward our galaxy at 200,000 miles per hour.

This motion can only be accounted for by gravitational attraction, even though the mass that we can observe is not nearly great enough to exert that kind of pull. The only thing that could explain the movement of Andromeda is the gravitational pull of a lot of unseen mass--perhaps the equivalent of 10 Milky Way-size galaxies--lying between the two galaxies.

Meanwhile, our entire Local Group is hurtling toward the center of the Virgo Cluster (image above) at one million miles per hour.

The Milky Way and its neighboring Andromeda galaxy, along with some 30 smaller ones, form what is known as the Local Group, which lies on the outskirts of a “super cluster”—a grouping of thousands of galaxies—known as Virgo, which is also pulled toward the Great Attractor. Based on the velocities at these scales, the unseen mass inhabiting the voids between the galaxies and clusters of galaxies amounts to perhaps 10 times more than the visible matter.

Even so, adding this invisible material to luminous matter brings the average mass density of the universe still to within only 10-30 percent of the critical density needed to "close" the universe. This phenomena suggests that the universe be "open." Cosmologists continue to debate this question, just as they are also trying to figure out the nature of the missing mass, or "dark matter."

It is believed that this dark matter dictates the structure of the Universe on the grandest of scales. Dark matter gravitationally attracts normal matter, and it is this normal matter that astronomers see forming long thin walls of super-galactic clusters.

Recent measurements with telescopes and space probes of the distribution of mass in M31 -the largest galaxy in the neighborhood of the Milky Way- and other galaxies led to the recognition that galaxies are filled with dark matter and have shown that a mysterious force—a dark energy—fills the vacuum of empty space, accelerating the universe's expansion.

Astronomers now recognize that the eventual fate of the universe is inextricably tied to the presence of dark energy and dark matter.The current standard model for cosmology describes a universe that is 70 percent dark energy, 25 percent dark matter, and only 5 percent normal matter.

We don't know what dark energy is, or why it exists. On the other hand, particle theory tells us that, at the microscopic level, even a perfect vacuum bubbles with quantum particles that are a natural source of dark energy. But a naïve calculation of the dark energy generated from the vacuum yields a value 10120 times larger than the amount we observe. Some unknown physical process is required to eliminate most, but not all, of the vacuum energy, leaving enough left to drive the accelerating expansion of the universe.

A new theory of particle physics is required to explain this physical process.The new "dark attractor" theories skirt the so-called Copernican principle that posits that there is nothing special about us as observers of the universe suggesting that the universe is not homogeneous. These alternative theories explain the observed accelerated expansion of the universe without invoking dark energy, and instead assume we are near the center of a void, beyond which a denser "dark" attractor pulls outwards.

In a paper appearing in Physical Review Letters, Pengjie Zhang at the Shanghai Astronomical Observatory and Albert Stebbins at Fermilab show that a popular void model, and many others aiming to replace dark energy, don’t stand up against telescope observation.

Galaxy surveys show the universe is homogeneous, at least on length scales up to a gigaparsec. Zhang and Stebbins argue that if larger scale inhomogeneities exist, they should be detectable as a temperature shift in the cosmic microwave background—relic photons from about 400,000 years after the big bang—that occurs because of electron-photon (inverse Compton) scattering.

Focusing on the “Hubble bubble” void model, they show that in such a scenario, some regions of the universe would expand faster than others, causing this temperature shift to be greater than what is expected. But telescopes that study the microwave background, such as the Atacama telescope in Chile or the South Pole telescope, don’t see such a large shift.

Though they can’t rule out more subtle violations of the Copernican principle, Zhang and Stebbins’ test reinforces Carl Sagan's dictum that "extraordinary claims require extraordinary evidence."

The Daily Galaxy via PhysRevLett.107.041301 and http://www.nasa.gov/mission_pages/hubble/science/great-attractor.html

Alien Planet Discovery a Puzzle --Accepted Theory Says "It Can't Exist"

2013-06-18T03:20:00-07:00

A team of researchers has discovered evidence that an extrasolar planet may be forming quite far from its star—- about twice the distance Pluto is from our Sun. Planet formation far away from a small parent star is at odds with the conventional planet-making dogma. Under the most accepted scenario, planets form over tens of millions of years from the slow accretion of dust, rocks, and gas. That happens most easily close to the central star, where orbital timescales are short. Even under a disk instability scenario, in which planets can collapse quickly from the disk, it's not clear such a low mass planet could form. Carnegie Institute astrophysicist Alan Boss, who works on disk instability models, said "If the mass of this suspected planet is as low as it seems to be, this presents a real puzzle. Theory would say that it cannot exist!"

The planet lies inside a dusty, gaseous disk around a small red dwarf TW Hydrae, which is only about 55 percent of the mass of the Sun. The discovery adds to the ever-increasing variety of planetary systems in the Milky Way. This dusty protoplanetary disk is the closest one to us, some 176 light-years away in the constellation Hydra.

The astronomers made Hubble Space Telescope observations over a wide range of wavelengths from visible to near infrared and modeled the color and structure of the disk in a way that has not been done before. They found a deficit of disk material, or partial gap, at about 80 astronomical units (AU) (1 AU is the Earth/Sun distance). Their models indicate that the depression is about 20 AUs wide, just slightly wider than necessary for a planet-opening gap and consistent with a planet of between 6 and 28 Earth masses. The feature is seen at all wavelengths indicating it is structural and not a local compositional difference. The team believes the evidence is strong for planet formation causing the gap.

"TW Hydrae is between 5 and 10 million years old, and should be in the final throes of planet formation before its disk dissipates," remarked coauthor Alycia Weinberger of the Carnegie Institution and principal investigator of the observations. "It is surprising to find a planet only 5 to 10% of Jupiter's mass forming so far out since planets should form faster closer in. In all planet formation scenarios, it's difficult to make a low-mass planet far away from a low mass star."

The goal of these observations was to understand not only whether planets have formed, but also what conditions can result in planet formation and what chemical constituents are available for new planets. Models by coauthor Hannah Jang-Condell, a former Carnegie postdoctoral researcher, showed that the disk was brighter than expected, which indicates that very small dust grains are being lifted high above the midplane. This is surprising because observations with radio telescopes have previously shown that the disk contains dust that has conglomerated into pebbles.

Weinberger designed the observations to be able to detect large water ice grains in the surface layer of the disk. These grains weren't seen, which probably means that they have grown and sunk to the midplane of the disk where they can aggregate into water-rich planets.

Lead author of the study, John Debes of the Space Science Telescope Institute and also a former Carnegie postdoctoral researcher remarked, "Typically, you need pebbles before you can form a planet. So, if there is a planet in the gap and there is no dust larger than a grain of sand farther out, we have provided a challenge for traditional planet formation models."

The Chandra Observatory illustration at the top of the page depicts matter accreting onto TW Hydrae from a circumstellar disk. X-rays are produced as matter from the disk is guided by the star's magnetic field onto one or more hot spots on the surface of the star. On the right, the illustration shows a binary star system's brightest star producing X-rays much as the Sun does, from a hot upper atmosphere or corona. This indicates that any disk around these stars has been greatly diminished or destroyed in ten million years, perhaps by the ongoing formation of planets or by its companion stars.

The research is published in the Astrophysical Journal.

The Daily Galaxy via Carnegie Institute

Image Credit: NASA, ESA, J. Debes (STScI), H. Jang-Condell (University of Wyoming), A. Weinberger (Carnegie Institution of Washington), A. Roberge (Goddard Space Flight Center), and G. Schneider (University of Arizona/Steward Observatory)

A Moment of Zen (!) --Lewis Black on Google Glass, Robots & Immortality

2013-06-18T02:00:00-07:00

Lewis Black on Comedy Central

The 'Daily Galaxy' Followers Soar Above 270,000!

2013-06-18T00:10:00-07:00

Join the 272,000 Daily Galaxy fans around the world who follow us via their Twitter page. Our followers include many of the planet's leading astronomers and scientists, astronauts, space observatories, news organizations, universities and governmental space organizations such as NASA, JPL, ESO, SETI, Harvard-Smithsonian Center for Astrophysics (CfA) and Royal Astronomy Society members. Follow us daily at twitter.com/dailygalaxy

Image Credit: With thanks to Vikram K. Mulligan. Used with permission

Outer Space Mystery --"The Missing Oxygen Molecule"

2013-06-17T08:58:04-07:00

A 2012 search for molecular oxygen in the Orion Nebula came up negative, leading to new ideas on what's wrong in the chemical models. Searches for interstellar molecular oxygen, O2, have a long history, and the motivation for these searches has evolved. Prior to the late 1990’s, efforts to detect O2 were driven by a desire to confirm its predicted role as a major reservoir of elemental oxygen within dense molecular clouds and as the most important gas coolant of typical clouds after carbon monoxide (CO). But O2 was never found. The SAO-led Submillimeter Wave Astronomy Satellite (SWAS) in 1998 and the Odin satellite in 2001 both failed to detect O2 toward a large number of sources at levels of a few percent of the abundances predicted by equilibrium gas-phase chemical models. Something in the chemical models was wrong, but what?

The conclusion forced a shift in the emphasis of searches. Today, interest in O2 no longer lies in its being a significant reservoir of elemental oxygen or in its cooling power. Instead, the searches have become an important way to test our current understanding of interstellar chemistry, and the various key formation, destruction, and depletion processes for O2 and the balance between them.

Harvard Center for Astrophysics (CfA) astronomers Gary Melnick and Volker Tolls led a team of nineteen astronomers using the Herschel Space Observatory in study of O2 in the Orion nebula, a location well known for its rich chemistry. Herschel instruments have both high sensitivity and the broad wavelength coverage needed to search for the molecule in several of its emission lines.

The scientists report that they still did not find O2. The improved sensitivity, however, allows them to reach some general, if preliminary conclusions about four issues: the way oxygen clings to ice in the interstellar medium (perhaps stronger than previously suspected), the amount of total material in the Orion region (less than had been thought), the way O2 clumps together (smaller clumps), and the location of these molecules in the clouds (buried deeper than previous estimates).

Further modeling and additional observations will clarify the situation further, but the present work goes a long way to narrowing the possible explanations for the mysterious absence of this life-giving molecule.

The image at the top of the page shows the nebula's glowing gas surrounding hot young stars at the edge of an immense interstellar molecular cloud only 1500 light-years away. Visible simultaneously are the bright stars of the Trapezium in Orion's heart, the sweeping lanes of dark dust that cross the center, the red glowing hydrogen gas, and the blue tinted dust that reflects the light of newborn stars. The whole Orion Nebula cloud complex, which includes the Horsehead Nebula, will slowly disperse over the next 100,000 years.

Journal reference: Astrophysical Journal

The Daily Galaxy via Harvard-Smithsonian Center for Astrophysics

Image credit: With thanks to Robert Gendler

Long-Standing Black Hole Mystery Solved

2013-06-17T07:54:39-07:00

The Chandra X-Ray Observatory image above highlights the black hole, Sagittarius A*, at the Milky Way's galactic center, which lies in the heart of the constellation of Sagittarius at a distance of ~8 kiloparsecs from the Sun. Monitoring of x-ray emissions over the last decade has shown a very massive central object, now clearly identified as a ~3 million solar-mass black hole. The radio emissions at the core of the image show a compact non-thermal source at the central massive black hole (Sgr A*), spiral-shaped streams of gas falling onto Sgr A* (Sgr A West), and the ring-shaped supernova remnant shown here (Sgr A East).

A mystery that has stymied astrophysicists for decades is: "how do black holes produce so many high-power X-rays?" In a new study, astrophysicists from The Johns Hopkins University, NASA and the Rochester Institute of Technology conducted research that bridges the gap between theory and observation by demonstrating that gas spiraling toward a black hole inevitably results in X-ray emissions.

“Black holes are truly exotic, with extraordinarily high temperatures, incredibly rapid motions and gravity exhibiting the full weirdness of general relativity,” said Julian Krolik, professor of physics and astronomy. “But our calculations show we can understand a lot about them using only standard physics principles.”

The paper says that as gases spiral toward a black hole through a formation called an accretion disk, it heats up to roughly 10 million degrees Celsius. The temperature in the main body of the disk is roughly 2,000 times hotter than the sun and emits low-energy or “soft” X-rays. However, observations also detect “hard” X-rays which produce up to 100 times higher energy levels.

Krolik and his fellow scientists used a combination of supercomputer simulations and traditional hand-written calculations to uncover their findings. Supported by 40 years of theoretical progress, the team showed for the first time that high-energy light emission is not only possible, but is an inevitable outcome of gas being drawn into a black hole.

The team’s work was recently published in the print edition of Astrophysical Journal. His collaborators on the study include Jeremy Schnittman, a research astrophysicist from the NASA Goddard Space Flight Center, and Scott Noble, an associate research scientist from the Center for Computational Relativity and Gravitation at RIT. Schnittman was lead author.

As the quality and quantity of the high-energy light observations improved over the years, evidence mounted showing that photons must be created in a hot, tenuous region called the corona. This corona, boiling violently above the comparatively cool disk, is similar to the corona surrounding the sun, which is responsible for much of the ultra-violet and X-ray luminosity seen in the solar spectrum.

While the team’s study of black holes and high-energy light confirms a widely-held belief, the role of advancing modern technology should not be overlooked.

Noble developed the computer simulation solving all of the equations governing the complex motion of inflowing gas and its associated magnetic fields near an accreting black hole. The rising temperature, density and speed of the inflowing gas dramatically amplify magnetic fields threading through the disk, which then exert additional influence on the gas.

The result is a turbulent froth orbiting the black hole at speeds approaching the speed of light. The calculations simultaneously tracked the fluid, electrical and magnetic properties of the gas while also taking into account Einstein’s theory of relativity.

“In some ways, we had to wait for technology to catch up with us,” Krolik said. “It’s the numerical simulations going on at this level of quality and resolution that make the results credible.”

The Daily Galaxy via Johns Hopkins

"Dark Galaxies" --Were They the Building Blocks of the Galaxies We See Today?

2013-06-17T06:00:00-07:00

Dark galaxies are essentially devoid of stars, therefore they don’t emit any light that telescopes can catch. This makes them virtually impossible to observe unless they are illuminated by an external light source like a background quasar. The image above combines observations from the Very Large Telescope, tuned to detect the fluorescent emissions produced by the quasar illuminating the dark galaxies, with colour data from the Digitized Sky Survey 2. Dark galaxies are small, gas-rich galaxies in the early Universe predicted by theories of galaxy formation, and are thought to be the building blocks of today's bright, star-filled galaxies. Astronomers think that they may have fed large galaxies with much of the gas that later formed into the stars that exist today.

Because they are essentially devoid of stars, these dark galaxies don't emit much light, making them very hard to detect. For years astronomers have been trying to develop new techniques that could confirm the existence of these galaxies. Small absorption dips in the spectra of background sources of light have hinted at their existence. A 2012 study marked the first time that such objects were seen directly.

"Our approach to the problem of detecting a dark galaxy was simply to shine a bright light on it." explains Simon Lilly (ETH Zurich, Switzerland), co-author of the paper. "We searched for the fluorescent glow of the gas in dark galaxies when they are illuminated by the ultraviolet light from a nearby and very bright quasar. The light from the quasar makes the dark galaxies light up in a process similar to how white clothes are illuminated by ultraviolet lamps in a night club."

The team took advantage of the large collecting area and sensitivity of the Very Large Telescope (VLT), and a series of very long exposures, to detect the extremely faint fluorescent glow of the dark galaxies. They used the FORS2 instrument to map a region of the sky around the bright quasar HE 0109-3518, looking for the ultraviolet light that is emitted by hydrogen gas when it is subjected to intense radiation. Because of the expansion of the Universe, this light is actually observed as a shade of violet by the time it reaches the VLT.

Quasars are very bright, distant galaxies that are believed to be powered by supermassive black holes at their centres. Their brightness makes them powerful beacons that can help to illuminate the surrounding area, probing the era when the first stars and galaxies were forming out of primordial gas.* "After several years of attempts to detect fluorescent emission from dark galaxies, our results demonstrate the potential of our method to discover and study these fascinating and previously invisible objects," says Sebastiano Cantalupo (University of California, Santa Cruz), lead author of the study.

The team detected almost 100 gaseous objects which lie within a few million light-years of the quasar. After a careful analysis designed to exclude objects where the emission might be powered by internal star-formation in the galaxies, rather than the light from the quasar, they finally narrowed down their search to 12 objects. These are the most convincing identifications of dark galaxies in the early Universe to date.

The astronomers were also able to determine some of the properties of the dark galaxies. They estimate that the mass of the gas in them is about 1 billion times that of the Sun, typical for gas-rich, low-mass galaxies in the early Universe. They were also able to estimate that the star formation efficiency is suppressed by a factor of more than 100 relative to typical star-forming galaxies found at similar stage in cosmic history.

"Our observations with the VLT have provided evidence for the existence of compact and isolated dark clouds. With this study, we've made a crucial step towards revealing and understanding the obscure early stages of galaxy formation and how galaxies acquired their gas", concludes Sebastiano Cantalupo.

The MUSE integral field spectrograph, which will be commissioned on the VLT in 2013, will be an extremely powerful tool for the study of these objects.

The Daily Galaxy via Royal Astronomical Society

Image credit: ESO, Digitized Sky Survey 2 and S. Cantalupo (UCSC)

"Cosmic Flows" --Mapping the Movements of the Galaxies

2013-06-15T08:57:23-07:00

An international team of researchers has mapped the motions of structures of the nearby universe in greater detail than ever before. The maps are presented as a video, which provides a dynamic three-dimensional representation of the universe through the use of rotation, panning and zooming.

The Cosmic Flows project has mapped visible and dark matter densities around the Milky Way galaxy up to a distance of 300 million light-years.

The large-scale structure of the universe is a complex web of clusters, filaments, and voids. Large voids—relatively empty spaces—are bounded by filaments that form superclusters of galaxies, the largest structures in the universe. Our Milky Way galaxy lies in a supercluster of 100,000 galaxies.

Just as the movement of tectonic plates reveals the properties of Earth’s interior, the movements of the galaxies reveal information about the main constituents of the Universe: dark energy and dark matter. Dark matter is unseen matter whose presence can be deduced only by its effect on the motions of galaxies and stars because it does not give off or reflect light. Dark energy is the mysterious force that is causing the expansion of the universe to accelerate.

The video captures with precision not only the distribution of visible matter concentrated in galaxies, but also the invisible components, the voids and the dark matter. Dark matter constitutes 80 percent of the total matter of our universe and is the main cause of the motions of galaxies with respect to each other. This precision 3-D cartography of all matter (luminous and dark) is a substantial advance.

The correspondence between wells of dark matter and the positions of galaxies (luminous matter) is clearly established, providing a confirmation of the standard cosmological model. Through zooms and displacements of the viewing position, this video follows structures in three dimensions and helps the viewer grasp relations between features on different scales, while retaining a sense of orientation.

The scientific community now has a better representation of the moving distribution of galaxies around us and a valuable tool for future research.

The scientific article, “Cosmography of the Local Universe,” which explains the research behind the video, will be published in a forthcoming issue of The Astronomical Journal. It is now available at http://arxiv.org/abs/1306.0091.

Founded in 1967, the Institute for Astronomy at the University of Hawaiʻi at Mānoa conducts research into galaxies, cosmology, stars, planets, and the sun. Its faculty and staff are also involved in astronomy education, deep space missions, and in the development and management of the observatories on Haleakala and Mauna Kea. The Institute operates facilities on the islands of Oʻahu, Maui, and Hawaiʻi.

The Daily Galaxy via http://manoa.hawaii.edu/news/

EcoAlert: Is a Sleeping Climate-Change Monster Lurking Beneath the Arctic?

2013-06-15T05:50:00-07:00

"The Arctic is warming dramatically - two to three times faster than mid-latitude regions - yet we lack sustained observations and accurate climate models to know with confidence how the balance of carbon among living things will respond to climate change and related phenomena in the 21st century," said research scientist Charles Miller of NASA's Jet Propulsion Laboratory, Pasadena, Calif.. "Changes in climate may trigger transformations that are simply not reversible within our lifetimes, potentially causing rapid changes in the Earth system that will require adaptations by people and ecosystems."

Permafrost zones occupy nearly a quarter of the exposed land area of the Northern Hemisphere. NASA's Carbon in Arctic Reservoirs Vulnerability Experiment is probing deep into the frozen lands above the Arctic Circle in Alaska to measure emissions of the greenhouse gases carbon dioxide and methane from thawing permafrost - signals that may hold a key to Earth's climate future.

Flying low and slow above the wild, pristine terrain of Alaska's North Slope in a specially instrumented NASA plane Miller surveys the endless whiteness of tundra and frozen permafrost below. On the horizon, a long, dark line appears. The plane draws nearer, and the mysterious object reveals itself to be a massive herd of migrating caribou, stretching for miles. It's a sight Miller won't soon forget.

"Seeing those caribou marching single-file across the tundra puts what we're doing here in the Arctic into perspective," said Miller, principal investigator of the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE), a five-year NASA-led field campaign studying how climate change is affecting the Arctic's carbon cycle.

"The Arctic is critical to understanding global climate," he said. "Climate change is already happening in the Arctic, faster than its ecosystems can adapt. Looking at the Arctic is like looking at the canary in the coal mine for the entire Earth system."

Aboard the NASA C-23 Sherpa aircraft from NASA's Wallops Flight Facility, Wallops Island, Va., Miller, CARVE Project Manager Steve Dinardo of JPL and the CARVE science team are probing deep into the frozen lands above the Arctic Circle. The team is measuring emissions of the greenhouse gases carbon dioxide and methane from thawing permafrost -- signals that may hold a key to Earth's climate future.

Permafrost (perennially frozen) soils underlie much of the Arctic. Each summer, the top layers of these soils thaw. The thawed layer varies in depth from about 4 inches (10 centimeters) in the coldest tundra regions to several yards, or meters, in the southern boreal forests. This active soil layer at the surface provides the precarious foothold on which Arctic vegetation survives. The Arctic's extremely cold, wet conditions prevent dead plants and animals from decomposing, so each year another layer gets added to the reservoirs of organic carbon sequestered just beneath the topsoil.

Over hundreds of millennia, Arctic permafrost soils have accumulated vast stores of organic carbon - an estimated 1,400 to 1,850 petagrams of it (a petagram is 2.2 trillion pounds, or 1 billion metric tons). That's about half of all the estimated organic carbon stored in Earth's soils. In comparison, about 350 petagrams of carbon have been emitted from all fossil-fuel combustion and human activities since 1850. Most of this carbon is located in thaw-vulnerable topsoils within 10 feet (3 meters) of the surface.

But, as scientists are learning, permafrost - and its stored carbon - may not be as permanent as its name implies. And that has them concerned.

"Permafrost soils are warming even faster than Arctic air temperatures - as much as 2.7 to 4.5 degrees Fahrenheit (1.5 to 2.5 degrees Celsius) in just the past 30 years," Miller said. "As heat from Earth's surface penetrates into permafrost, it threatens to mobilize these organic carbon reservoirs and release them into the atmosphere as carbon dioxide and methane, upsetting the Arctic's carbon balance and greatly exacerbating global warming."

Current climate models do not adequately account for the impact of climate change on permafrost and how its degradation may affect regional and global climate. Scientists want to know how much permafrost carbon may be vulnerable to release as Earth's climate warms, and how fast it may be released.

Enter CARVE. Now in its third year, this NASA Earth Ventures program investigation is expanding our understanding of how the Arctic's water and carbon cycles are linked to climate, as well as what effects fires and thawing permafrost are having on Arctic carbon emissions. CARVE is testing hypotheses that Arctic carbon reservoirs are vulnerable to climate warming, while delivering the first direct measurements and detailed regional maps of Arctic carbon dioxide and methane sources and demonstrating new remote sensing and modeling capabilities. About two dozen scientists from 12 institutions are participating.

The CARVE team flew test flights in 2011 and science flights in 2012. This April and May, they completed the first two of seven planned monthly campaigns in 2013, and they are currently flying their June campaign.

Each two-week flight campaign across the Alaskan Arctic is designed to capture seasonal variations in the Arctic carbon cycle: spring thaw in April/May, the peak of the summer growing season in June/July, and the annual fall refreeze and first snow in September/October. From a base in Fairbanks, Alaska, the C-23 flies up to eight hours a day to sites on Alaska's North Slope, interior and Yukon River Valley over tundra, permafrost, boreal forests, peatlands and wetlands.

The C-23 won't win any beauty contests - its pilots refer to it as "a UPS truck with a bad nose job." Inside, it's extremely noisy - the pilots and crew wear noise-cancelling headphones to communicate. "When you take the headphones off, it's like being at a NASCAR race," Miller quipped.

But what the C-23 lacks in beauty and quiet, it makes up for in reliability and its ability to fly "down in the mud," so to speak. Most of the time, it flies about 500 feet (152 meters) above ground level, with periodic ascents to higher altitudes to collect background data. Most airborne missions measuring atmospheric carbon dioxide and methane do not fly as low. "CARVE shows you need to fly very close to the surface in the Arctic to capture the interesting exchanges of carbon taking place between Earth's surface and atmosphere," Miller said.

Onboard the plane, sophisticated instruments "sniff" the atmosphere for greenhouse gases. They include a very sensitive spectrometer that analyzes sunlight reflected from Earth's surface to measure atmospheric carbon dioxide, methane and carbon monoxide. This instrument is an airborne simulator for NASA's Orbiting Carbon Observatory-2 (OCO-2) mission to be launched in 2014. Other instruments analyze air samples from outside the plane for the same chemicals. Aircraft navigation data and basic weather data are also collected. Initial data are delivered to scientists within 12 hours. Air samples are shipped to the University of Colorado's Institute for Arctic and Alpine Research Stable Isotope Laboratory and Radiocarbon Laboratory in Boulder for analyses to determine the carbon's sources and whether it came from thawing permafrost.

Much of CARVE's science will come from flying at least three years, Miller says. "We are showing the power of using dependable, low-cost prop planes to make frequent, repeat measurements over time to look for changes from month to month and year to year."

Ground observations complement the aircraft data and are used to calibrate and validate them. The ground sites serve as anchor points for CARVE's flight tracks. Ground data include air samples from tall towers and measurements of soil moisture and temperature to determine whether soil is frozen, thawed or flooded.

It's important to accurately characterize the soils and state of the land surfaces. There's a strong correlation between soil characteristics and release of carbon dioxide and methane. Historically, the cold, wet soils of Arctic ecosystems have stored more carbon than they have released. If climate change causes the Arctic to get warmer and drier, scientists expect most of the carbon to be released as carbon dioxide. If it gets warmer and wetter, most will be in the form of methane.

The distinction is critical. Molecule per molecule, methane is 22 times more potent as a greenhouse gas than carbon dioxide on a 100-year timescale, and 105 times more potent on a 20-year timescale. If just one percent of the permafrost carbon released over a short time period is methane, it will have the same greenhouse impact as the 99 percent that is released as carbon dioxide. Characterizing this methane to carbon dioxide ratio is a major CARVE objective.

There are other correlations between Arctic soil characteristics and the release of carbon dioxide and methane. Variations in the timing of spring thaw and the length of the growing season have a major impact on vegetation productivity and whether high northern latitude regions generate or store carbon.

CARVE is also studying wildfire impacts on the Arctic's carbon cycle. Fires in boreal forests or tundra accelerate the thawing of permafrost and carbon release. Detailed fire observation records since 1942 show the average annual number of Alaska wildfires has increased, and fires with burn areas larger than 100,000 acres are occurring more frequently, trends scientists expect to accelerate in a warming Arctic. CARVE's simultaneous measurements of greenhouse gases will help quantify how much carbon is released to the atmosphere from fires in Alaska - a crucial and uncertain element of its carbon budget.

The CARVE science team is busy analyzing data from its first full year of science flights. What they're finding, Miller said, is both amazing and potentially troubling.

"Some of the methane and carbon dioxide concentrations we've measured have been large, and we're seeing very different patterns from what models suggest," Miller said. "We saw large, regional-scale episodic bursts of higher-than-normal carbon dioxide and methane in interior Alaska and across the North Slope during the spring thaw, and they lasted until after the fall refreeze. To cite another example, in July 2012 we saw methane levels over swamps in the Innoko Wilderness that were 650 parts per billion higher than normal background levels. That's similar to what you might find in a large city."

Ultimately, the scientists hope their observations will indicate whether an irreversible permafrost tipping point may be near at hand. While scientists don't yet believe the Arctic has reached that tipping point, no one knows for sure. "We hope CARVE may be able to find that 'smoking gun,' if one exists," Miller said.

Other institutions participating in CARVE include City College of New York; the joint University of Colorado/National Oceanic and Atmospheric Administration's Cooperative Institute for Research in Environmental Sciences, Boulder, Colo.; San Diego State University; University of California, Irvine; California Institute of Technology, Pasadena; Harvard University, Cambridge, Mass.; University of California, Berkeley; Lawrence Berkeley National Laboratory, Berkeley, Calif.; University of California, Santa Barbara; NOAA's Earth System Research Laboratory, Boulder, Colo.; and University of Melbourne, Victoria, Australia.

The Daily Galaxy via http://science.nasa.gov/missions/carve/

"Mars is Not a Dead Planet" --Meteorite and Glaciation Evidence Point to Profound Climate Change Cycles

2013-06-15T04:00:00-07:00

"Mars is not a dead planet -it undergoes climate changes that are even more pronounced than on Earth," says James Head, planetary geologist, Brown University. The prevailing thinking is that Mars is a planet whose active climate has been confined to the distant past. About 3.5 billion years ago, the Red Planet had extensive flowing water and then fell quiet - deadly quiet. It didn't seem the climate had changed much since. Now, recent studies by scientists at Brown University show that Mars' climate has been much more dynamic than previously believed.

Just this week, researchers from the University of Hawaii at Manoa NASA Astrobiology Institute (UHNAI) have discovered high concentrations of boron in a Martian meteorite. When present in its oxidized form (borate), boron may have played a key role in the formation of RNA, one of the building blocks for life.

The Antarctic Search for Meteorites team found the Martian meteorite used in this study in Antarctica during its 2009-2010 field season. The minerals it contains, as well as its chemical composition, clearly show that it is of Martian origin. Using the ion microprobe in the W. M. Keck Cosmochemistry Laboratory at UH, the team was able to analyze veins of Martian clay in the meteorite. After ruling out contamination from Earth, they determined boron abundances in these clays are over ten times higher than in any previously measured meteorite.

"Borates may have been important for the origin of life on Earth because they can stabilize ribose, a crucial component of RNA. In early life RNA is thought to have been the informational precursor to DNA," said James Stephenson, a UHNAI postdoctoral fellow.
RNA may have been the first molecule to store information and pass it on to the next generation, a mechanism crucial for evolution. Although life has now evolved a sophisticated mechanism to synthesize RNA, the first RNA molecules must have been made without such help. One of the most difficult steps in making RNA nonbiologically is the formation of the RNA sugar component, ribose. Previous laboratory tests have shown that without borate the chemicals available on the early Earth fail to build ribose. However, in the presence of borate, ribose is spontaneously produced and stabilized.

After examining stunning high-resolution images taken by the Reconnaissance Orbiter, researchers in 2009 documented for the first time that ice packs at least 1 kilometer (0.6 miles) thick and perhaps 2.5 kilometers (1.6 miles) thick existed along Mars' mid-latitude belt as recently as 100 million years ago. In addition, the team believes other images tell them that glaciers flowed in localized areas in the last 10 to 100 million years - a blink of the eye in Mars's geological timeline.

This evidence of recent activity means the Martian climate may change again and could bolster speculation about whether the Red Planet can, or did, support life.

"We've gone from seeing as a dead planet for three-plus billion years to one that has been alive in recent times," said Jay Dickson, a research analyst in the Department of Geological Sciences at Brown. "[The finding] has changed our perspective from a planet that has been dry and dead to one that is icy and active."

In fact, Dickson and his co-authors, James Head, and David Marchant, a associate professor at Boston University, believe the images show that has gone through multiple Ice Ages - episodes in its recent past in which the planet's mid-latitudes were covered by glaciers that disappeared with changes in the Red Planet's obliquity, which changes the climate by altering the amount of sunlight falling on different areas.

NASA's Global Surveyor and Odyssey missions have provided evidence of a relatively recent ice age on Mars. In contrast to Earth's ice ages, a Martian ice age expands when the poles warm, and water vapor is transported toward lower latitudes. Martian ice ages wane when the poles cool and lock water into polar icecaps.

The catalysts of ice ages on appear to be much more extreme than the comparable drivers of climate change on Earth. Variations in the planet's orbit and tilt produce remarkable changes in the distribution of water ice from Polar Regions down to latitudes equivalent to Houston or Egypt. Researchers, using NASA spacecraft data and analogies to Earth's Antarctic Dry Valleys, reported their findings in the journal Nature.

"Of all the solar system planets, has the climate most like that of Earth. Both are sensitive to small changes in orbital parameters," said Head. "Now we're seeing that Mars, like Earth, is in a period between ice ages," he said. This evidence of recent activity means the Martian climate may change again and could bolster speculation about whether the Red Planet can, or did, support life.

Head and his team examined global patterns of landscape shapes and near-surface water ice Nasa's orbiters mapped. They concluded a covering of water ice mixed with dust mantled the surface of to latitudes as low as 30 degrees, and is degrading and retreating. By observing the small number of impact craters in those features and by backtracking the known patterns of changes in Mars' orbit and tilt, they estimated the most recent ice age occurred just 400 thousand to 2.1 million years ago.

Marchant, a glacial geologist who spent 17 field seasons in the Mars-like Antarctic Dry Valleys, said, "These extreme changes on Mars provide perspective for interpreting what we see on Earth. Landforms on that appear to be related to climate changes help us calibrate and understand similar landforms on Earth. Furthermore, the range of microenvironments in the Antarctic Dry Valleys helps us read the Mars record."

According to the researchers, during a Martian ice age, polar warming drives water vapor from polar ice into the atmosphere. The water comes back to ground at lower latitudes as deposits of frost or snow mixed generously with dust. This ice-rich mantle, a few meters thick, smooths the contours of the land. It locally develops a bumpy texture at human scales, resembling the surface of a basketball, and also seen in some Antarctic icy terrains. When ice at the top of the mantling layer sublimes back into the atmosphere, it leaves behind dust, which forms an insulating layer over remaining ice. On Earth, by contrast, ice ages are periods of polar cooling. The buildup of ice sheets draws water from liquid-water oceans, which lacks.

Dickson and the other researchers focused on an area called Protonilus Mensae-Coloe Fossae. The region is located in Mars's mid-latitude and is marked by splotches of mesas, massifs and steep-walled valleys that separate the lowlands in the north from the highlands in the south.

The team looked in particular at a box canyon set in a low-lying plain. Images show the canyon has moraines - deposits of rocks that mark the limits of a glacier's advance or the path of its retreat. The rock deposit lines appear to show a glacier that flowed up the box canyon, which "physically cannot happen," Dickson said.

Instead, the team deduced the ice in the surrounding plain grew higher than the canyon's walls and then flowed downward onto the top of the canyon, which had become the lowest point on the ice-laden terrain. The team calculated the ice pack must have been one kilometer thick by past measurements of height between the plain and the lip of the canyon. Based on the ice flow patterns, the ice pack could have reached 2.5 kilometers at peak thickness during a period known as the late Amazonian, the authors said.

The finding could have implications for the life-on-argument by strengthening the case for liquid water. Ice can melt two ways: by temperature or by pressure. As currently understood, the Martian climate is dominated by sublimation, the process by which solid substances are transformed directly to vapor. But ice packs can exert such strong pressure at the base to produce liquid water, which makes the thickness of past glaciers on its surface so intriguing.

Dickson also looked at a lobe across the valley from the box canyon site. There, he saw a clear, semi-circular moraine that had spilled from an ancient tributary on to the surrounding plain. The lobe is superimposed on a past ice deposit and appears to be evidence of more recent glaciation. Although geologists can't date either event, the landscape appears to show at least two periods in which glaciation occurred, bolstering their theory that the Martian climate has undergone past Ice Ages.

"Earth and Mars used to have much more in common than they do today," says Lydia Hallis, a cosmochemist who is also a UHNAI postdoctoral fellow. "Over time, Mars has lost a lot of its atmosphere and surface water, but ancient meteorites preserve delicate clays from wetter periods in Mars' history. The Martian clay we studied is thought to be up to 700 million years old. The recycling of the Earth's crust via plate tectonics has left no evidence of clays this old on our planet; hence Martian clays could provide essential information regarding environmental conditions on the early Earth."

The image at the top of the pages shows Phlegra Montes, a range of gently curving mountains and ridges on Mars. Images from the high-resolution stereo camera on ESA’s Mars Express orbiter allowed a closer inspection and show that almost every mountain is surrounded by ‘lobate debris aprons’ – curved features typically observed around plateaus and mountains at these latitudes. Previous studies have shown that this material appears to have moved down the mountain slopes over time, and looks similar to the debris found covering glaciers here on Earh, suggesting that there may be glaciers buried just below the surface in this region.

The Daily Galaxy via University of Hawaii; http://news.brown.edu/pressreleases/2008/04/martian-glaciers;
http://www.nasa.gov/home/hqnews/2003/dec/HQ_03415_ice_age.html

26 New Black Holes Found In Andromeda, Our Sister Galaxy

2013-06-13T14:43:19-07:00

Using more than 150 Chandra X-ray Observatory observations, spread over 13 years, researchers identified 26 black hole candidates, the largest number to date, in the Andromeda Galaxy, one of the nearest galaxies to the Milky Way. Many consider Andromeda to be a sister galaxy to the Milky Way. The two ultimately will collide, several billion years from now.

"While we are excited to find so many black holes in Andromeda, we think it's just the tip of the iceberg," said Robin Barnard of Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., and lead author of a new paper describing these results. "Most black holes won't have close companions and will be invisible to us."

The black hole candidates belong to the stellar mass category, meaning they formed in the death throes of very massive stars and typically have masses five to 10 times that of our sun. Astronomers can detect these otherwise invisible objects as material is pulled from a companion star and heated up to produce radiation before it disappears into the black hole.

The first step in identifying these black holes was to make sure they were stellar mass systems in the Andromeda Galaxy itself, rather than supermassive black holes at the hearts of more distant galaxies. To do this, the researchers used a new technique that draws on information about the brightness and variability of the X-ray sources in the Chandra data. In short, the stellar mass systems change much more quickly than the supermassive black holes.

To classify those Andromeda systems as black holes, astronomers observed that these X-ray sources had special characteristics: that is, they were brighter than a certain high level of X-rays and also had a particular X-ray color. Sources containing neutron stars, the dense cores of dead stars that would be the alternate explanation for these observations, do not show both of these features simultaneously. But sources containing black holes do.

The European Space Agency's XMM-Newton X-ray observatory added crucial support for this work by providing X-ray spectra, the distribution of X-rays with energy, for some of the black hole candidates. The spectra are important information that helps determine the nature of these objects.

"By observing in snapshots covering more than a dozen years, we are able to build up a uniquely useful view of M31," said co-author Michael Garcia, also of CfA. "The resulting very long exposure allows us to test if individual sources are black holes or neutron stars."

The research group previously identified nine black hole candidates within the region covered by the Chandra data, and the present results increase the total to 35. Eight of these are associated with globular clusters, the ancient concentrations of stars distributed in a spherical pattern about the center of the galaxy. This also differentiates Andromeda from the Milky Way as astronomers have yet to find a similar black hole in one of the Milky Way's globular clusters.

Seven of these black hole candidates are within 1,000 light-years of the Andromeda Galaxy's center. That is more than the number of black hole candidates with similar properties located near the center of our own galaxy. This is not a surprise to astronomers because the bulge of stars in the middle of Andromeda is bigger, allowing more black holes to form.

"When it comes to finding black holes in the central region of a galaxy, it is indeed the case where bigger is better," said co-author Stephen Murray of Johns Hopkins University and CfA. "In the case of Andromeda we have a bigger bulge and a bigger supermassive black hole than in the Milky Way, so we expect more smaller black holes are made there as well."

This new work confirms predictions made earlier in the Chandra mission about the properties of X-ray sources near the center of M31. Earlier research by Rasmus Voss and Marat Gilfanov of the Max Planck Institute for Astrophysics in Garching, Germany, used Chandra to show there was an unusually large number of X-ray sources near the center of M31. They predicted most of these extra X-ray sources would contain black holes that had encountered and captured low mass stars. This new detection of seven black hole candidates close to the center of M31 gives strong support to these claims.

"We are particularly excited to see so many black hole candidates this close to the center, because we expected to see them and have been searching for years," said Barnard.

The image at the top of the page shows the beautiful but strange center of the Andromeda galaxy. Andromeda, indexed as M31, is so close to our own Milky Way Galaxy that it gives a unique perspective into galaxy composition by allowing us to see into its core. Billions of stars swarm around a center that has two nuclei and likely houses a supermassive black hole over 5 million times the mass of our Sun.

These results will be published in the June 20 issue of The Astrophysical Journal. Many of the Andromeda observations were made within Chandra's Guaranteed Time Observer program.

Galaxy Clusters Reveal Distribution of Dark Matter

2013-06-13T06:00:00-07:00

“Each bright city light is a galaxy, and the dark areas between the lights that appear to be empty during the night are actually full of dark matter. You can think of the dark matter in a galaxy cluster as being the infrastructure within which the galaxies live,” say an international team of astronomers from Taiwan, UK, Japan, and the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA). The researchers used a large sample of galaxy clusters to find out how the density of dark matter changes from the center of a typical galaxy cluster to its outskirts.has used the Subaru Telescope to measure the density of dark matter in fifty galaxy clusters and found that its density gradually decreases from the center of these cosmic giants to their diffuse outskirts. This new evidence about the mysterious dark matter that pervades our Universe conforms to the predictions of cold dark matter theory, known as “CDM”.

Almost all of the bright objects in the Hubble Space Telescope image above are galaxies in the cluster known as Abell 2218. The cluster is so massive and so compact that its gravity bends and focuses the light from galaxies that lie behind it. As a result, multiple images of these background galaxies are distorted into long faint arcs - a simple lensing effect analogous to viewing distant street lamps through a glass of wine. The cluster of galaxies Abell 2218 is itself about two billion light-years away in the northern constellation Draco. Three images of this young, still-maturing galaxy are faintly visible in the white contours near the image top and the lower right. The recorded light, further analyzed with a Keck Telescope, left this galaxy when the universe was only about five percent of its current age.

Few scientists seriously doubt the existence of dark matter, which researchers discovered almost eighty years ago. Nevertheless, astronomers cannot directly see dark matter in the night sky, and particle physicists have not yet identified a dark matter particle in their experiments. “What is dark matter?” is a big unanswered question facing astronomers and particle physicists, especially because invisible dark matter probably makes up 85% of the mass of the Universe.

The current team, led by ASIAA Postdoctoral Fellow Nobuhiro Okabe and Dr. Graham Smith (University of Birmingham, England), used the Subaru Prime Focus Camera (Suprime-Cam) to investigate the nature of dark matter by measuring its density in fifty galaxy clusters, the most massive objects in the Universe. “A galaxy cluster is like a huge city viewed from above during the night”, explained Smith.

The density of dark matter depends on the properties of the individual dark matter particles, just like the density of everyday materials depends on their components. CDM, the leading theory about dark matter to date, predicts that dark matter particles only interact with each other and with other matter via the force of gravity; they do not emit or absorb electromagnetic radiation and are difficult if not impossible to see.

The team chose to observe dark matter by using gravitational lensing, which detects its presence through its gravitational interactions with ordinary matter and radiation. According to Einstein’s theory of relativity, light from a very distant bright source bends around a massive object, e.g., a cluster of galaxies, between the source object and the observer. It follows from this principle that the dark matter in cosmic giants like galaxy clusters alters the apparent shape and position of distant galaxies. Lead author Okabe enthused, “The Subaru Telescope is a fantastic instrument for gravitational lensing measurements. It allows us to measure very precisely how the dark matter in galaxy clusters distorts light from distant galaxies and gauge tiny changes in the appearance of a huge number of faint galaxies.”

CDM theory describes how dark matter in galaxy clusters changes from its dense center to its lower density edges in two ways. One is a simple measure of the galaxy cluster’s mass, the amount of matter that it contains. The other is a concentration parameter, which is a single measurement of the cluster’s average density, how compact it is. CDM theory predicts that central regions of galaxy clusters have a low concentration parameter while individual galaxies have a high concentration parameter.

The team combined measurements from observations of fifty of the most massive known galaxy clusters to calculate their concentration parameter. They found that the density of dark matter increases from the edges to the center of the cluster, and that the concentration parameter of galaxy clusters in the near Universe aligns with CDM theory. The averaged mass map (attachment) is remarkably symmetrical with a pronounced mass peak. The mass density distribution for individual clusters shows a wide range of densities.

Past research based on a small number of clusters found that they had large concentration parameters and did not conform to CDM theory. Measurement of the average concentration parameter from a large number of clusters yielded a different result, which supports CDM theory. Okabe commented on the team’s findings, based on a larger sample of galaxy clusters: “This is a very satisfying result, which is based on a very careful analysis of the best available data”.

What does the future hold for the team’s continued research on dark matter? Smith noted, “We don’t stop here. For example, we can improve our work by measuring dark matter density on even smaller scales, right in the center of these galaxy clusters. Additional measurements on smaller scales will help us to learn more about dark matter in the future.”

The study was published online in The Astrophysical Journal Letters on May 17, 2013. The full article entitled “LoCuSS: The Mass Density Profile of Massive Galaxy Clusters at z=0.2” is available at The Astrophysical Journal Letters website at: http://iopscience.iop.org/2041-8205/769/2/L35/pdf/2041-8205_769_2_L35.pdf

The Daily Galaxy via http://www.sinica.edu.tw/

Ancient Hydrogen Signals --a Key to the Evolution of the Universe

2013-06-13T05:00:00-07:00

“Hydrogen is the building block of the Universe, it’s what stars form from and what keeps a galaxy ‘alive’,” said Jacinta Delhaize a researcher with theInternational Centre for Radio Astronomy Research (ICRAR). In research published in the Monthly Notices of the Royal Astronomical Society, Delhaize has studied distant galaxies en masse to determine one of their important properties – how much hydrogen they contain – by ‘stacking’ their signals. “Galaxies in the past formed stars at a much faster rate than galaxies now. We think that past galaxies had more hydrogen, and that might be why their star formation rate is higher."

“Distant, younger, galaxies look very different to nearby galaxies, which means that they’ve changed, or evolved, over time,” said Delhaize. “The challenge is to try and figure out what physical properties within the galaxy have changed, and how and why this has happened.”

Delhaize and her supervisors set out to observe how much hydrogen was in far away galaxies, but the faint radio signals of this distant hydrogen gas are almost impossible to detect directly. This is where the new stacking technique comes in.

To gather enough data for her research, Delhaize combined weak signals from thousands of individual galaxies, stacking them to produce a strong averaged signal that is easier to study.

“What we are trying to achieve with stacking is sort of like detecting a faint whisper in a room full of people shouting,” said Delhaize. “When you combine together thousands of whispers, you get a shout that you can hear above a noisy room, just like combining the radio light from thousands of galaxies to detect them above the background.”

The research used CSIRO’s Parkes radio telescope to survey a large section of the sky for 87 hours, collecting signals from hydrogen over an unmatched volume of space and up to two billion years back in time.

“The Parkes telescope views a big section of the sky at once, so it was quick to survey the large field we chose for our study,” said ICRAR Deputy Director and Jacinta’s supervisor, Professor Lister Staveley-Smith.

Delhaize said observing such a large volume of space meant that she could accurately calculate the average amount of hydrogen in galaxies at a certain distance from Earth, corresponding to a particular period in the Universe’s history. This provides information that can be used in simulations of the Universe’s evolution and clues to how galaxies formed and changed over time.

Next generation telescopes like the international Square Kilometre Array (SKA) and CSIRO’s Australian SKA Pathfinder (ASKAP) will be able to observe even larger volumes of the Universe with higher resolution.

“That makes them fast, accurate and perfect for studying the distant Universe. We can use the stacking technique to get every last piece of valuable information out of their observations,” said Delhaize. “Bring on ASKAP and the SKA!”

The combined graphic below shows a high-resolution image (inset) from the Green Bank Telescope of recently discovered hydrogen clouds between the Andromeda Galaxy M31 (upper right) and Triangulum Galaxy M33 (bottom left).

The Daily Galaxy via The Monthly Notices of the Royal Astronomical Society are published by Oxford University Press.

Image credit: Bill Saxton, NRAO/AUI/NSF

"Saturn Can Vibrate Like a Bell" --Creating Spirals in the Ancient Rings

2013-06-12T07:35:22-07:00

Saturn can vibrate like a bell within periods of a few hours, and these oscillations cause gravitational tugs that, in turn, create the spiral patterns in the rings. The cause of the vibrations remains unknown. Researchers at Cornell found the density waves propagate inward and appear to be generated from within Saturn rather than from any moon. Astronomers know that gravity from Saturn’s various moons tug at the planet’s rings and make spirals in them. But the catalyst for certain spiral patterns has been difficult to pin down.

“The locations and properties of these ring disturbances tell us how and with what periods the planet oscillates,” said senior research associate Matthew Hedman, whose new research was published June 11 in The Astronomical Journal. He also presented the research May 9 at the meeting of the American Astronomical Society’s Division for Dynamical Astronomy in Paraty, Brazil. “Just like earthquakes can be used to study the Earth’s interior, and solar oscillations can be used to study the interior of the sun, these vibrations in Saturn can help scientists figure out the internal structure of the giant planets.”

Saturn’s rings act as a seismograph that records these large-scale oscillations, possibly emanating from deep within the planet. The study of these records provides a completely new way to probe structure and rotation of Saturn’s interior, and the astronomers have come up with a name for it: kronoseismology.

Saturn’s oscillations are similar to what are called “whole earth oscillations” in terrestrial seismology. On Earth, these are generated by very large earthquakes, which make the Earth ring for several days.

The researchers focused on a handful of unexplained waves in Saturn’s C ring that did not appear to be linked to well-understood gravitational interactions with anything within or outside of the rings. They used data from NASA’s Cassini mission, which has repeatedly profiled Saturn’s rings using “stellar occultations” via the spacecraft’s Visual and Infrared Mapping Spectrometer instrument. The measurements record changes in light from a given star as the rings pass between the star and the spacecraft. Using numerous occultation measurements of the C ring, the researchers were able to piece together dossiers on these unexplained ring features.

The researchers found the density waves propagate inward and appear to be generated from within Saturn rather than from any moon; the six waves also have the right pattern speeds and symmetry properties to be produced by oscillations within Saturn.

The paper, “Kronoseismology: Using Density Waves in Saturn’s C Ring to Probe the Planet’s Interior,” was co-authored by Philip Nicholson, Cornell professor of astronomy.

The Daily Galaxy via http://news.cornell.edu

Image Credit: NASA

New Unknown Type of Star Discovered

2013-06-12T07:10:10-07:00

A Swiss team from the famous Geneva Observatory has achieved extraordinary precision using a comparatively small 1.2-metre telescope for an observing programme stretching over many years. They have discovered a new class of variable stars by measuring minute variations in stellar brightness in the open star cluster NGC 3766 in the constellation of Centaurus (The Centaur), and is estimated to be about 20 million years old.

"The very existence of this new class of variable stars is a challenge to astrophysicists," says Sophie Saesen, a team member. "Current theoretical models predict that their light is not supposed to vary periodically at all, so our current efforts are focused on finding out more about the behaviour of this strange new type of star."

The new results are based on regular measurements of the brightness of more than three thousand stars in the open star cluster NGC 3766 over a period of seven years. They reveal how 36 of the cluster's stars followed an unexpected pattern — they had tiny regular variations in their brightness at the level of 0.1% of the stars' normal brightness. These variations had periods between about two and 20 hours. The stars are somewhat hotter and brighter than the Sun, but otherwise apparently unremarkable. The new class of variable stars is yet to be given a name.

This level of precision in the measurements is twice as good as that achieved by comparable studies from other telescopes — and sufficient to reveal these tiny variations for the first time.

"We have reached this level of sensitivity thanks to the high quality of the observations, combined with a very careful analysis of the data," says Nami Mowlavi, leader of the research team, "but also because we have carried out an extensive observation programme that lasted for seven years. It probably wouldn't have been possible to get so much observing time on a bigger telescope."

Many stars are known as variable or pulsating stars, because their apparent brightness changes over time. How the brightness of these stars changes depends in complex ways on the properties of their interiors. This phenomenon has allowed the development of a whole branch of astrophysics called asteroseismology, where astronomers can "listen" to these stellar vibrations, in order to probe the physical properties of the stars and get to know more about their inner workings.

Although the cause of the variability remains unknown, there is a tantalising clue: some of the stars seem to be fast rotators. They spin at speeds that are more than half of their critical velocity, which is the threshold where stars become unstable and throw off material into space.

"In those conditions, the fast spin will have an important impact on their internal properties, but we are not able yet to adequately model their light variations," explains Mowlavi. "We hope our discovery will encourage specialists to address the issue in the hope of understanding the origin of these mysterious variations."

The Daily Galaxy via ESO

The "Ocean Moon" --Future Missions to Explore Jupiter's Europa

2013-06-11T07:46:46-07:00

Jupiter's Europa might not only sustain, but foster life, according to the research of University of Arizona's Richard Greenberg, a professor of planetary sciences and member of the Imaging Team for NASA's Galileo Jupiter-orbiter spacecraft. The deepest ocean on Earth is the Pacific Ocean's Marianas Trench, which reaches a depth of 6.8 miles awesomely trumped by the depth of the ocean on the Jupiter's moon, Europa, which some measurements put at 62 miles. Although Europa is covered in a thick crust of scarred and cross-hatched ice, measurements made by NASA's Galileo spacecraft and other probes strongly suggest that a liquid ocean lies beneath that surface. The interior is warmed, researchers believe, by the tidal stresses exerted on Europa by Jupiter and several other large moons, as well as by radioactivity.

Most scientists believe that the sub-Europan seas are locked under tens of kilometers of ice. Heat is then conducted from the warm core by bulk convective motion of ice - huge chunks of frozen material literally carrying the heat away with them as they move up through the icy layer, shuffling and refreezing as they dump heat into space.

With Jupiter being the largest planet in the solar system, its tidal stresses on Europa create enough heat to keep the water on Europa in a liquid state. More than just water is needed to support life. Tides also play a role in providing for life. Ocean tides on Europa are much greater in size than Earth's with heights reaching 500 meters (more than 1,600 feet). Even the shape of the moon is stretched along the equator due to Jupiter's pull on the waters below the icy surface.

The mixing of substances needed to support life is also driven by tides. Stable environments are also necessary for life to flourish. Europa, whose orbit around Jupiter is in-sync with its rotation, is able to keep the same face towards the gas giant for thousands of years. The ocean is interacting with the surface, according to Greenberg, and "there is a possible that extends from way below the surface to just above the crust."

"The real key to life on Europa," Greenburg adds, "is the permeability of the ice crust. There is strong evidence that the ocean below the ice is connected to the surface through cracks and melting, at various times and places. As a result, the , if there is one, includes not just the liquid water ocean, but it extends through the ice up to the surface where there is access to oxidants, organic compounds, and light for photosynthesis. The physical setting provides a variety of potentially habitable and evolving niches. If there is life there, it would not necessarily be restricted to microorganisms."

Europa has long been considered a potential hotspot for life in the Solar System. NASA's Astrobio.net reports that one of the first visitors to Jupiter's icy moon of Europa could be a tiny submarine barely larger than two soda cans. The small craft might help strike the right balance between cost and capability for a robotic mission to look for alien life in the ocean beneath Europa's icy crust.

The idea for the incredible shrinking submarine originally came from NASA’s Jet Propulsion Laboratory (JPL) in California and Uppsala University in Sweden. Such a vehicle (image below) would help keep mission costs low at a time when launching objects into space can still cost tens of thousands of dollars per kilogram. The mission concept also would have the advantage of only requiring a small borehole drilled through the ice covering Europa's surface.

"What I think is exciting with this is to be able to explore previously inaccessible areas, to explore where no "man" has explored before," said Jonas Jonsson, an engineer now with Stinger Ghaffarian Technologies Inc. at NASA Ames Research Center in Moffett Field, Calif.

A paper study of the miniature submersible first came from NASA JPL researchers and Greger Thornell’s Swedish team at Angstrom Space Technology Centre of Uppsala University. But Jonsson, an original member of the Swedish team, refined the submersible concept by building and testing parts of it for his Ph.D. thesis.

Scientists have gravitated toward the possibility of life on Europa ever since the Voyager 2 mission first scouted out the icy moon from afar in 1979. Voyager 2's images and data hinted at the existence of a liquid water ocean lurking beneath Europa's icy surface — a huge body of water bigger than all of Earth's oceans combined.

The existence of Arctic bacteria living under extreme frigid conditions on Earth suggests that life could possibly survive on icy Europa as well. But any life on Europa would only survive by hiding deep beneath Europa's crust — an icy covering about several kilometers (1 or 2 miles) in thickness — because of the radiation from Jupiter's magnetosphere bombarding the moon's surface.

Such intense radiation means a robotic lander digging a few feet into Europa's icy surface would likely find no organic traces or signs of life. Instead, a robotic mission might have better luck by going deep beneath the icy crust to study Europa's ocean.

Jonsson envisions the tiny submarine named Deeper Access, Deeper Understanding (DADU) taking on the Europa challenge in his 2012 Ph.D. thesis for Uppsala University in Sweden. The submarine could first get its feet wet by exploring similar watery environments on Earth where its small size could prove exceptionally useful.

"A mission to explore Lake Vostok in Antarctica, which is believed to have been isolated from the rest of the world by kilometers of thick ice for millions of years, would of course be the 'Holy Grail' mission, and a real proof of concept for a future mission to explore the oceans thought to exist underneath some of the frozen moons in the solar system, such as Europa and Enceladus," Jonsson explained.

The DADU submersible would use eight small thrusters to maneuver around the underwater world. A fiber optic tether would connect DADU to a surface lander or station — a way to recharge the submersible's lithium-ion batteries and allow for remote control by a human operator. On-board software would allow the submersible to automatically dodge obstacles or stay at a certain depth underwater.

A model of Europa's interior, including a global ocean. If a 100 kilometer-deep ocean existed below Europa’s ice shell, it would be 10 times deeper than any ocean on Earth and would contain twice as much water as Earth's oceans and rivers combined. Credit: NASA/JPL
The Swedish team created a series of miniaturized instruments and sensors for the dream submersible. DADU has a forward-looking camera with a small laser to capture high-resolution video and to gauge the distance, size and shape of underwater objects.

But a huge challenge came from shrinking everything down to incredibly small sizes. The sensor for measuring the conductivity, temperature and depth of water is smaller than a fingernail.

The submersible's sonar device alone could fit within a matchstick box, Jonsson said. Such a device uses piezoelectric material that can vibrate to create acoustic sonar pulses and read reflected pulses or vibrations as electrical signals.

Jonsson also tested the idea for the submersible's sampling device for collecting tiny life forms on Europa — a microfluidic device smaller than a human thumb with a special filter to trap tiny microorganisms.

The first prototypes of the DADU submersible were made of plastic from 3D printers that allowed the team to quickly "print" the digital designs into real objects. But they envision the real submersible being built from a titanium alloy in order to survive the harsh temperatures and intense pressures of underwater environments.

Next up, the Swedish team hopes to further refine the miniaturized instruments. They also need to build the full integrated systems with all the miniaturized electronics before they can seriously test the submersible's capability to survive in a frigid ocean — whether on Earth or on Europa.

"I don’t think there are any particular technological breakthroughs required," Jonsson said. "There exist possible solutions for the technological barriers; however, further developments and optimizations are required for such a mission to succeed."

Getting down beneath the ice is still far from simple. Any Europa mission designed to penetrate the moon's icy surface would require a mole-like drill to melt its way through the ice. The submersible would also need kilometers of tether connecting it to a surface lander or station in order to communicate with its remote human operator.

Nobody is seriously planning a landing mission on Europa yet. But the European Space Agency aims to launch its JUpiter ICy moons Explorer mission (JUICE) to make the first thickness measurements of Europa's icy crust starting in 2030. NASA also has begun planning a Europa Clipper mission that would study the icy moon while doing flybys in a Jupiter orbit.

The Daily Galaxy via NASA and Astrobio.net

"Anapole Dark Matter" --New Theory Explains Why Dark Matter Has Escaped Detection

2013-06-11T07:02:10-07:00

"Most models for dark matter assume that it interacts through exotic forces that we do not encounter in everyday life. Anapole dark matter makes use of ordinary electromagnetism that you learned about in school – the same force that makes magnets stick to your refrigerator or makes a balloon rubbed on your hair stick to the ceiling," said Robert Scherrer, a theoretical physicists at Vanderbilt University. "Further, the model makes very specific predictions about the rate at which it should show up in the vast dark matter detectors that are buried underground all over the world. These predictions show that soon the existence of anapole dark matter should either be discovered or ruled out by these experiments."

The bulk of the atter in the universe may be made out of particles that possess an unusual, donut-shaped electromagnetic field called an anapole. This new theory, which endows dark matter particles with a rare form of electromagnetism, has been strengthened by a detailed analysis performed by aScherrer and post-doctoral fellow Chiu Man Ho.

"There are a great many different theories about the nature of dark matter. What I like about this theory is its simplicity, uniqueness and the fact that it can be tested," said Scherrer.

In the article, titled "Anapole Dark Matter," the physicists propose that dark matter, an invisible form of matter that makes up 85 percent of the all the matter in the universe, may be made out of a type of basic particle called the Majorana fermion. The particle's existence was predicted in the 1930's but has stubbornly resisted detection.

A number of physicists have suggested that dark matter is made from Majorana particles, but Scherrer and Ho have performed detailed calculations that demonstrate that these particles are uniquely suited to possess a rare, donut-shaped type of electromagnetic field called an anapole. This field gives them properties that differ from those of particles that possess the more common fields possessing two poles (north and south, positive and negative) and explains why they are so difficult to detect.

Fermions are particles like the electron and quark, which are the building blocks of matter. Their existence was predicted by Paul Dirac in 1928. Ten years later, shortly before he disappeared mysteriously at sea, Italian physicist Ettore Majorana produced a variation of Dirac's formulation that predicts the existence of an electrically neutral fermion. Since then, physicists have been searching for Majorana fermions. The primary candidate has been the neutrino, but scientists have been unable to determine the basic nature of this elusive particle.

The existence of dark matter was also first proposed in the 1930's to explain discrepancies in the rotational rate of galactic clusters. Subsequently, astronomers have discovered that the rate that stars rotate around individual galaxies is similarly out of sync. Detailed observations have shown that stars far from the center of galaxies are moving at much higher velocities than can be explained by the amount of visible matter that the galaxies contain. Assuming that they contain a large amount of invisible "dark" matter is the most straightforward way to explain these discrepancies.

Scientists hypothesize that dark matter cannot be seen in telescopes because it does not interact very strongly with light and other electromagnetic radiation. In fact, astronomical observations have basically ruled out the possibility that dark matter particles carry electrical charges.

More recently, though, several physicists have examined dark matter particles that don't carry electrical charges, but have electric or magnetic dipoles. The only problem is that even these more complicated models are ruled out for Majorana particles. That is one of the reasons that Ho and Scherrer took a closer look at dark matter with an anapole magnetic moment.

"Although Majorana fermions are electrically neutral, fundamental symmetries of nature forbid them from acquiring any electromagnetic properties except the anapole," Ho said. The existence of a magnetic anapole was predicted by the Soviet physicist Yakov Zel'dovich in 1958. Since then it has been observed in the magnetic structure of the nuclei of cesium-133 and ytterbium-174 atoms.

Particles with familiar electrical and magnetic dipoles, interact with electromagnetic fields even when they are stationary. Particles with anapole fields don't. They must be moving before they interact and the faster they move the stronger the interaction. As a result, anapole particles would have been have been much more interactive during the early days of the universe and would have become less and less interactive as the universe expanded and cooled.

The anapole dark matter particles suggested by Ho and Scherrer would annihilate in the early universe just like other proposed dark matter particles, and the left-over particles from the process would form the dark matter we see today. But because dark matter is moving so much more slowly at the present day, and because the anapole interaction depends on how fast it moves, these particles would have escaped detection so far, but only just barely.

The Daily Galaxy via Vanderbilt University

Top of Page Dark Matter X-Ray Image Credit: NASA/SAO/CXC

Image of the Day: Sculptor Galaxy's Black Hole "On/Off" Cycle

2013-06-11T05:00:00-07:00

Nearly a decade ago, NASA's Chandra X-ray Observatory caught signs of what appeared to be a black hole snacking on gas at the middle of the nearby Sculptor galaxy. Now, NASA's Nuclear Spectroscopic Telescope Array (NuSTAR), which sees higher-energy X-ray light, has taken a peek and found the black hole asleep.

"Our results imply that the black hole went dormant in the past 10 years," said Bret Lehmer of the Johns Hopkins University, Baltimore, and NASA's Goddard Space Flight Center, Greenbelt, Md. "Periodic observations with both Chandra and NuSTAR should tell us unambiguously if the black hole wakes up again. If this happens in the next few years, we hope to be watching." Lehmer is lead author of a new study detailing the findings in the Astrophysical Journal.

The slumbering black hole is about 5 million times the mass of our sun. It lies at the center of the Sculptor galaxy, also known as NGC 253, a so-called starburst galaxy actively giving birth to new stars. At 13 million light-years away, this is one of the closest starbursts to our own galaxy, the Milky Way.

The Milky Way is all around more quiet than the Sculptor galaxy. It makes far fewer new stars, and its behemoth black hole, about 4 million times the mass of our sun, is also snoozing.

"Black holes feed off surrounding accretion disks of material. When they run out of this fuel, they go dormant," said co-author Ann Hornschemeier of Goddard. "NGC 253 is somewhat unusual because the giant black hole is asleep in the midst of tremendous star-forming activity all around it."

The findings are teaching astronomers how galaxies grow over time. Nearly all galaxies are suspected to harbor supermassive black holes at their hearts. In the most massive of these, the black holes are thought to grow at the same rate that new stars form, until blasting radiation from the black holes ultimately shuts down star formation. In the case of the Sculptor galaxy, astronomers do not know if star formation is winding down or ramping up.

"Black hole growth and star formation often go hand-in-hand in distant galaxies," said Daniel Stern, a co-author and NuSTAR project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "It's a bit surprising as to what's going on here, but we've got two powerful complementary X-ray telescopes on the case."

Chandra first observed signs of what appeared to be a feeding supermassive black hole at the heart of the Sculptor galaxy in 2003. As material spirals into a black hole, it heats up to tens of millions of degrees and glows in X-ray light that telescopes like Chandra and NuSTAR can see.

Then, in September and November of 2012, Chandra and NuSTAR observed the same region simultaneously. The NuSTAR observations -- the first-ever to detect focused, high-energy X-ray light from the region -- allowed the researchers to say conclusively that the black hole is not accreting material. NuSTAR launched into space in June of 2012.

In other words, the black hole seems to have fallen asleep. Another possibility is that the black hole was not actually awake 10 years ago, and Chandra observed a different source of X-rays. Future observations with both telescopes may solve the puzzle.

"The combination of coordinated Chandra and NuSTAR observations is extremely powerful for answering questions like this," said Lou Kaluzienski, NuSTAR Program Scientist at NASA Headquarters in Washington. "Now, we can get all sides of the story."

The observations also revealed a smaller, flaring object that the researchers were able to identify as an "ultraluminous X-ray source," or ULX. ULXs are black holes feeding off material from a partner star. They shine more brightly than typical stellar-mass black holes generated from dying stars, but are fainter and more randomly distributed than the supermassive black holes at the centers of massive galaxies. Astronomers are still working to understand the size, origins and physics of ULXs.

"These stellar-mass black holes are bumping along near the center of this galaxy," said Hornschemeier. "They tend to be more numerous in areas where there is more star-formation activity."

If and when the Sculptor's slumbering giant does wake up in the next few years amidst all the commotion, NuSTAR and Chandra will monitor the situation. The team plans to check back on the system periodically.

NuSTAR is a Small Explorer mission led by the California Institute of Technology in Pasadena and managed by NASA's Jet Propulsion Laboratory, also in Pasadena, for NASA's Science Mission Directorate in Washington. The spacecraft was built by Orbital Sciences Corporation, Dulles, Va. Its instrument was built by a consortium including Caltech; JPL; the University of California, Berkeley; Columbia University, New York; NASA's Goddard Space Flight Center, Greenbelt, Md.; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory, Livermore, Calif.; ATK Aerospace Systems, Goleta, Calif., and with support from the Italian Space Agency (ASI) Science Data Center.

NuSTAR's mission operations center is at UC Berkeley, with the ASI providing its equatorial ground station located at Malindi, Kenya. The mission's outreach program is based at Sonoma State University, Rohnert Park, Calif. NASA's Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.

500 Billion --A Universe of Galaxies: Some Older than Milky Way

2013-06-10T07:54:27-07:00

he Hubble Space Telescope site estimates there are hundreds of billions of galaxies in the universe. A recent German super-computer simulation estimates that the number may be as high as 500 billion, with many older than the Milky Way. Common obervational wisdom among astronomers is that there are 17 billion Earth-sized planets in our galaxy. They don't yet know how many of these worlds are in habitable zones, but the implications of this discovery are astounding. Simply put: If there are 17 billion Earth-sized worlds in our galaxy alone, it's clear that the Universe has the potential to be teeming with life.

A team of scientists lead by Francois Fressin of the Harvard-Smithsonian Center for Astrophysics, used the latest data from NASA's Kepler mission to find that one in six stars have "a planet 0.8 - 1.25 times the size of Earth in an orbit of 85 days or less." Extrapolated out to the Universe as a whole, the potential number becomes mind-boggling.

With the advent of powerful space infrared telescopes like the Spitzer Space Telescope and the (recently deceased) Herschel Space Telescope, astronomers have been able to study the properties of dust in galaxies so remote that their light has been traveling towards us for over ninety percent of the age of the universe. That these distant objects are detected at all is because they are very bright in the infrared, and they are bright because they are making huge numbers of stars whose light warms the dust that in turn radiates at infrared wavelengths.

In the image below A field of distant galaxies as seen at long infrared wavelengths over a region about one-third the size of the moon. The poor spatial resolution of infrared telescopes coupled with the great distances of the galaxies preclude seeing their spiral (or other) structures, but their different colors are apparent. A new study of 2500 distant infrared galaxies concludes they are more varied than local galaxies, probably due to different kinds of dust and dusty conditions in these early objects.

Local galaxies - those only hundreds of millions of light-years away in our cosmic neighborhood - provide a template for understanding how galaxies behave, and are the basis for models of their distant cousins. It has been known for decades that the early universe was actively making stars in galaxies. A key question for astronomers is whether distant galaxies are different enough from local ones that different physical processes need to be included in the models, or whether comparisons with local objects are valid.

CfA astronomer Ho Seong Hwang and a large team of his collaborators have analyzed a large sample of distant galaxies to address this question. The Herschel Space Telescope during its lifetime observed many distant infrared galaxies. The astronomers selected 2500 of them from a set of over fifty thousand, based on their having clear detections at several infrared wavelengths with ancillary data from other missions. The sample was selected in a way that was independent of observer preferences, like extreme brightness, that might compromise the conclusions, the first time this has been done for such a large sample.

The results were surprising. The scientists found that the dust in remote luminous galaxies tended to be warmer than it is in local galaxies of the same luminosity. Together with other indicators, the data suggest that the character of the dust and its environments have evolved with time in ways that are still not well known. Probably as a result of the dust variations there also appears to be a greater diversity of types of galaxies in the early universe.

Finally, the new paper notes, in accord with other recent papers, that there are indications that these galaxies may have started forming sooner after the big bang than had been anticipated in some old models.

In 2012, the Brightest of Reionizing Galaxies (BoRG) survey, which uses Hubble's WFC3 to search for the brightest galaxies around 13 billion years ago, when light from the first stars burned off a fog of cold hydrogen in a process called reionisation located five clustered galaxies so distant that their light has taken 13.1 billion years to reach us. We are seeing them just 600 million years after the Universe's birth in the Big Bang.

Galaxy clusters are the largest structures in the Universe, comprising hundreds to thousands of galaxies bound together by gravity. This developing cluster, or protocluster, seen as it looked 13 billion years ago, presumably has grown into one of today's massive cities of galaxies, comparable to the nearby Virgo cluster of more than 2000 galaxies.

"These galaxies formed during the earliest stages of galaxy assembly, when galaxies had just started to cluster together," says the study's leader, Michele Trenti (University of Cambridge, UK and University of Colorado). "The result confirms our theoretical understanding of the buildup of galaxy clusters. And, Hubble is just powerful enough to find the first examples of them at this distance."

Most galaxies in the Universe reside in groups and clusters, and astronomers have probed many of these in detail at a range of distances. But finding clusters in the early phases of construction has been challenging because they are rare and dim.

"We need to look in many different areas because the odds of finding something this rare are very small," says Trenti who used Hubble's sharp-eyed Wide Field Camera 3 (WFC3) to pinpoint the galaxy clusters. "It's like playing a game of Battleship: the search is hit and miss. Typically, a region has nothing, but if we hit the right spot, we can find multiple galaxies."

Because these distant, fledgling clusters are so dim, the team hunted for the systems' brightest galaxies. These brilliant galaxies act as billboards, advertising cluster construction zones. From simulations, the astronomers expect galaxies at early epochs to be clustered together. Because brightness correlates with mass, the most luminous galaxies pinpoint the location of developing clusters.

These powerful light beacons are found in deep wells of dark matter, an invisible form of matter that makes up the underlying gravitational scaffolding for galaxy formation. The team expects many fainter galaxies that were not seen in these observations to inhabit the same neighborhood.

The five bright galaxies spotted by Hubble are about one-half to one-tenth the size of our Milky Way, yet are comparable in brightness. The galaxies are bright and massive because they are being fed large amounts of gas through mergers with other galaxies. The team's simulations show that the galaxies will eventually merge and form the brightest central galaxy in the cluster, a giant elliptical radio similar to the Virgo Cluster's Messier 87 (image at top of page).

These observations demonstrate the progressive buildup of galaxies and provide further support for the hierarchical model of galaxy assembly, in which small objects accrete mass, or merge, to form bigger objects over a smooth and steady, but dramatic, process of collision and collection.

The team estimated the distance to the newly found galaxies based on their colors. Astronomers now plan to follow up with spectroscopic observations, which will help them precisely calculate the cluster's distance. These observations will also yield the velocities of the galaxies and show whether they are gravitationally bound to each other.

The image below at left, taken in visible and near-infrared light, reveals the location of five galaxies clustered together just 600 million years after the Universe’s birth in the Big Bang. The circles pinpoint the galaxies. The sharp-eyed Wide Field Camera 3 aboard the NASA/ESA Hubble Space Telescope spied the galaxies in a random sky survey.

The developing cluster is the most distant ever observed. The average distance between them is comparable to that of the galaxies in the Local Group, consisting of two large spiral galaxies, the Milky Way and the Andromeda Galaxy, and a few dozen small dwarf galaxies. The close-up images at right, taken in near-infrared light, show the galaxies.

Simulations show that the galaxies will eventually merge and form the brightest central galaxy in the cluster, a giant elliptical similar to the Virgo cluster’s Messier 87. Galaxy clusters are the largest structures in the Universe, comprising hundreds to thousands of galaxies bound together by gravity. The developing cluster presumably will grow into a massive galactic city, similar in size to the nearby Virgo Cluster, a collection of more than 2000 galaxies.

The Daily Galaxy via Cfa and ESA/Hubble Information Center

Image Credit: NASA, ESA, M. Trenti (University of Cambridge, UK and University of Colorado, Boulder, USA), L. Bradley (STScI), and the BoRG team; ESA GOOD-S

Dwarf Galaxy Found with Only 1,000 Stars Bound by Dark Matter

2013-06-10T07:04:50-07:00

The least massive galaxy in the known universe has been measured by UC Irvine scientists, clocking in at just 1,000 or so stars with a bit of dark matter holding them together. The findings, made with the world’s most powerful telescopes and published today in The Astrophysical Journal, offer tantalizing clues about how iron, carbon and other elements key to human life originally formed. But the size and weight of Segue 2, as the star body is called, are its most extraordinary aspects.

“Finding a galaxy as tiny as Segue 2 is like discovering an elephant smaller than a mouse,” said UC Irvine cosmologist James Bullock, co-author of the paper. Astronomers have been searching for years for this type of dwarf galaxy, long predicted to be swarming around the Milky Way. Their inability to find any, he said, “has been a major puzzle, suggesting that perhaps our theoretical understanding of structure formation in the universe was flawed in a serious way.”

Segue 2’s presence as a satellite of our home galaxy could be “a tip-of-the-iceberg observation, with perhaps thousands more very low-mass systems orbiting just beyond our ability to detect them,” he added.

“It’s definitely a galaxy, not a star cluster,” said postdoctoral scholar and lead author Evan Kirby. He explained that the stars are held together by a globule called a dark matter halo. Without this acting as galactic glue, the star body wouldn’t qualify as a galaxy.

Segue 2, discovered in 2009 as part of the massive Sloan Digital Sky Survey, is one of the faintest known galaxies, with light output just 900 times that of the sun. That’s miniscule compared to the Milky Way, which shines 20 billion times brighter. But despite its tiny size, researchers using different tools originally thought Segue 2 was far denser.

The image above shows a standard prediction for the dark matter distribution within about 1 million light years of the Milky Way galaxy, which is expected to be swarming with thousands of small dark matter clumps called `halos'. The scale of this image is such that the disk of the Milky Way would reside within the white region at the center. Until now, there was no observational evidence that dark matter actually clumps this way, raising concerns that our understanding of the cosmos was flawed in a fundamental way. Observations of Segue 2 (zoomed image) have revealed that it must reside within such a tiny dark matter halo, providing possibly the first observational evidence that dark matter is as clumpy as long predicted.

“W. M. Keck Observatory operates the only telescopes in the world powerful enough to have made this observation,” Kirby said of the huge apparatus housed on the summit of Mauna Kea in Hawaii. He determined the upper weight range of 25 of the major stars in the galaxy and found that it weighs at least 10 times less than previously estimated.

Fellow authors are Michael Boylan-Kolchin and Manoj Kaplinghat of UC Irvine, Judith Cohen of the California Institute of Technology and Marla Geha of Yale University. Funding was provided by the Southern California Center for Galaxy Evolution (a multicampus research program of the University of California) and by the National Science Foundation.

The Daily Galaxy via UC Irvine

Image Credit: Garrison-Kimmel, Bullock (UCI)

"God is Not a Good Theory" --To Explain the Existence of the Universe

2013-06-10T04:21:00-07:00

dailygalaxy.com

"Black Widow Pulsar"--At the Top of Strange Phenomena in the Universe?

2013-06-09T09:15:23-07:00

The pulsar, a.k.a. the "Black Widow," is moving through the galaxy at a speed of almost a million kilometers per hour. A bow shock wave due to this motion is visible to optical telescopes, shown in this image as the greenish crescent shape. The pressure behind the bow shock creates a second shock wave that sweeps the cloud of high-energy particles back from the pulsar to form the cocoon.

This composite Chandra X-ray (red/white) and optical (green/blue) image reveals an elongated cloud, or cocoon, of high-energy particles flowing behind the rapidly rotating pulsar, B1957+20 (white point-like source). The pulsar, a.k.a. the "Black Widow" pulsar, is moving through the galaxy at a speed of almost a million kilometers per hour. A bow shock wave due to this motion is visible to optical telescopes, shown in this image as the greenish crescent shape. The pressure behind the bow shock creates a second shock wave that sweeps the cloud of high-energy particles back from the pulsar to form the cocoon.

The pulsar is emitting intense high-energy radiation that appears to be destroying a companion star through evaporation. It is one of a class of extremely rapid rotating neutron stars called millisecond pulsars. Calculations suggest that the "black widow" will evaporate away its companion in about a billion years.

These objects are thought to be very old neutron stars that have been spun up to rapid rotation rates with millisecond periods by pulling material off their companions. The advanced age, very rapid rotation rate, and relatively low magnetic field of millisecond pulsars put them in a separate class from young pulsars, such as the Crab Nebula.

Pulsars rank at or near the top of freaky phenomena found in our Universe. In the early 1930s, California Institute of Technology astrophysicist, Fred Zwicky, an immigrant from Bulgaria, focused his attention on a question that had long troubled astronomers: the appearance of random, unexplained points of light, new stars.

It occurred to Zwicky that if a star collapsed to the sort of density found in the core of atoms, the result would be an unimaginably compacted core: atoms would be crushed together with their electrons squeezed into the nucleus, forming neutrons and a neutron star, with a core so dense that a single spoonful would weigh 200 billion pounds. But there's more, Zwicky concluded: with the collapse of the star there would be huge amounts of leftover energy that would result in a massive explosion, the biggest in the known universe that we called today supernovas.

Most neutron stars house incredibly large magnetic fields. If they are spinning rapidly they make fabulous clocks, cosmic radio beacons we call pulsars. Pulsars can keep time to an accuracy better that one microsecond per year. Some pulsars generate more than 1000 pulses per second, which means, as Lawrence Krauss wrote in The Physics of Star Trek, that an object with the mass of the Sun packed into an object 10 to 20 kilometers across is rotating over 1000 times per second, or more that half the speed of light!

The Daily Galaxy via chandra.harvard.edu

Image Credits: Chandra; X-ray: NASA/CXC/ASTRON/B.Stappers et al.; Optical: AAO/J.Bland-Hawthorn & H.Jones

"X-Points" --Space Portals Linking Earth to Sun's Magnetic Field (Weekend Feature)

2013-06-09T08:40:07-07:00

Data from NASA's Polar spacecraft, circa 1998, provided crucial clues to finding "portals" -- an extraordinary opening in space or time that connects travelers to distant realms. "We call them X-points or electron diffusion regions," explains plasma physicist Jack Scudder of the University of Iowa. "They're places where the magnetic field of Earth connects to the magnetic field of the Sun, creating an uninterrupted path leading from our own planet to the sun's atmosphere 93 million miles away."

Observations by NASA's THEMIS spacecraft and Europe's Cluster probes suggest that these magnetic portals open and close dozens of times each day. They're typically located a few tens of thousands of kilometers from Earth where the geomagnetic field meets the onrushing solar wind. Most portals are small and short-lived; others are yawning, vast, and sustained. Tons of energetic particles can flow through the openings, heating Earth's upper atmosphere, sparking geomagnetic storms, and igniting bright polar auroras.

NASA is planning a mission called "MMS," short for Magnetospheric Multiscale Mission, due to launch in 2014, to study the phenomenon. Bristling with energetic particle detectors and magnetic sensors, the four spacecraft of MMS will spread out in Earth's magnetosphere and surround the portals to observe how they work.

Just one problem: Finding them. Magnetic portals are invisible, unstable, and elusive. They open and close without warning "and there are no signposts to guide us in," notes Scudder.* Portals form via the process of magnetic reconnection. Mingling lines of magnetic force from the sun and Earth criss-cross and join to create the openings. "X-points" are where the criss-cross takes place. The sudden joining of magnetic fields can propel jets of charged particles from the X-point, creating an "electron diffusion region."

To learn how to pinpoint these events, Scudder looked at data from a space probe that orbited Earth more than 10 years ago.* "In the late 1990s, NASA's Polar spacecraft spent years in Earth's magnetosphere," explains Scudder, "and it encountered many X-points during its mission."

Because Polar carried sensors similar to those of MMS, Scudder decided to see how an X-point looked to Polar. "Using Polar data, we have found five simple combinations of magnetic field and energetic particle measurements that tell us when we've come across an X-point or an electron diffusion region. A single spacecraft, properly instrumented, can make these measurements."

This means that single member of the MMS constellation using the diagnostics can find a portal and alert other members of the constellation. Mission planners long thought that MMS might have to spend a year or so learning to find portals before it could study them. Scudder's work short cuts the process, allowing MMS to get to work without delay.* It's a shortcut worthy of the best portals of fiction, only this time the portals are real. And with the new "signposts" we know how to find them.

The work of Scudder and colleagues is described in complete detail in the June 1 issue of the Physical Review Letters.

The Daily Galaxy via Science@NASA

Search for Alien Life --Detecting Hidden Earth-Like Planets

2013-06-08T08:12:43-07:00

As part of an international team of exoplanets hunters, astronomers at the University of Arizona are developing a technique to detect faint dust clouds around other stars, many of which might hide Earth-like plan. If one looks only for the shiniest pennies in the fountain, chances are one misses most of the coins because they shimmer less brightly. This, in a nutshell, is the conundrum astronomers face when searching for Earth-like planets outside our solar system.

Astronomers at the University of Arizona are part of an international team of exoplanets hunters developing new technology that would dramatically improve the odds of discovering planets with conditions suitable for life – such as having liquid water on the surface.

The team presented its results at a scientific conference sponsored by the International Astronomical Union in Victoria, British Columbia.

Terrestrial planets orbiting nearby stars often are concealed by vast clouds of dust enveloping the star and its system of planets. Our solar system, too, has a dust cloud, which consists mostly of debris left behind by clashing asteroids and exhaust spewing out of comets when they pass by the sun.

"Current technology allows us to detect only the brightest clouds, those that are a few thousand times brighter than the one in our solar system," said Denis Defrère, a postdoctoral fellow in the UA's department of astronomy and instrument scientist of the Large Binocular Telescope Interferometer, or LBTI.

He explained that while the brighter clouds are easier to see, their intense glare makes detecting putative Earth-like planets difficult, if not impossible. "We want to be able to detect fainter dust clouds, which would dramatically increase our chances of finding more of these planets."

"If you see a dust cloud around a star, that's an indication of rocky debris, and it increases the likelihood of there being something Earth-like around that star," said Phil Hinz, an associate professor of astronomy at the UA's Steward Observatory.

"From previous observations, we know that these planets are fairly common," he added. "We can expect that if a space telescope dedicated to that mission were to look around a certain area of sky, we'd expect to find quite a few."

Hinz and Defrère are working on an instrument that will allow astronomers to detect fainter clouds that are only about 10 times – instead of several thousand times – brighter than the one in our solar system.

"It's like being here in Victoria and trying to image a firefly circling a lighthouse in San Francisco that is shrouded in fog," Defrère said about the technological challenge.

"That level of sensitivity is the minimum we need for future space telescope missions that are to characterize Earth-like planets that can sustain liquid water on the surface," he explained. "Our goal is to eliminate the dust clouds that are too bright from the catalog of candidates because they are not promising targets to detect planets suitable for life."

"With a bright dust cloud, which is 1,000 times brighter than the one in our solar system, its light becomes comparable to that of its star, which makes it easier to detect," explained Hinz.

Fainter clouds, on the other hand, can be about 10,000 times less bright than their star, so it becomes difficult or impossible for observers to make out their faint glow in the star's overpowering glare.

Funded by NASA, the team is in the middle of carrying out tests to demonstrate the feasibility of these observations using both apertures of the Large Binocular Telescope, or LBT, in Arizona. The project aims at determining how difficult it would be to achieve the desired results before committing to a billion-dollar space telescope mission.

According to Hinz, NASA's goal is to be able take a direct picture of Earth-like, rocky planets and record their spectrum of light to analyze their composition and characteristics such as temperature, presence of water and other parameters.

"To do that, one would need a space telescope specifically designed for this type of imaging," he said. "Our goal is to do a feasibility study of whether it would be possible to distinguish the light emission of the planet from the background emission of the dust cloud through direct observation."

The researchers take advantage of a technique known as nulling interferometry and the unique configuration of the LBT, which resembles a giant pair of binoculars.

"We combine the light from two apertures, cancel out the light from the central star, and with that it becomes easier to see the light from the dust cloud," Hinz explained. "To achieve this, we have to cause the two light paths to interfere with each other, which requires lining them up with very high precision. We'll always have some starlight left because of imperfections in the system, but our goal is to cancel it out to a level of 10,000 to get down to where we can at least detect the faint glow of the dust cloud."

The work presented at the conference used the same technique with the two large telescopes of the Keck Observatory in Hawaii in order to detect the dust cloud around the star Fomalhaut (image at top of page) located 25 light years from our sun.

"Based on our observations at the European Very Large Telescope Interferometer, we knew that Fomalhaut was surrounded by a bright dust cloud located very close to the star," said Jérémy Lebreton, principal investigator of the study, who is at the Institut de Planétologie et d'Astrophysique in Grenoble, France.

"Using the Keck Interferometer, we found out that Fomalhaut has a less bright, more diffuse cloud orbiting close to the habitable zone that resembles the Main Asteroid Belt in our solar system. This belt is likely in dynamical interaction with yet undetected planets."

Fomalhaut (Alpha Piscis Austrini), believed to be a young star, only 100 to 300 million years old, is approximately 25 light-years away, is the brightest star in the constellation Piscis Austrinus and one of the brightest stars in the sky. Fomalhaut is metal-deficient as compared to the Sun, which means it is composed of a smaller percentage of elements other than hydrogen and helium.

Fomalhaut is surrounded by a doughnut-shaped debris disk with a very sharp inner edge. This dusty disk is believed to be protoplanetary, and emits considerable infrared radiation. Measurements of Fomalhaut’s rotation indicate that the disk is located in the star’s equatorial plane, as expected from theories of star and planet formation.

In November 2008, astronomers announced the discovery of an extrasolar planet, a Jupiter-sized planet called Fomalhaut b, orbiting just inside the debris ring. But later work revealed that the candidate planet was behaving strangely — its brightness varied, and its orbit was wrong, what means that it isn’t sure the candidate planet is there. Early 2012 new observations paint a picture of a ring with unexpectedly well-defined edges — the trademark handiwork of shepherd planets.

The study presented here is one in a series of three publications and was conducted in collaboration with the University of Amsterdam; the University of Liège in Belgium; NASA's Jet Propulsion Laboratory at Caltech, Pasadena, Calif.; the University of Paris; and the University of Arizona in Tucson, Ariz.

Approximately 250 scientists from around the world convened at the scientific conference, Exploring the Formation and Evolution of Planetary Systems, held June 3-7 in Victoria to discuss the latest observations and theories about exoplanetary systems.

The Daily Galaxy via University of Arizona