This photo shows the images of 9 superdense compact objects, as they were 11 billion of years ago.

Elliptical galaxies are the most massive of the near-Earth universe. These galaxies are oval shaped and regular, and do not have a disk like the spirals of the Milky Way. Using large telescopes, astronomers have identified elliptical galaxies 10 times more massive than our own galaxy, the Milky Way, and are approximately 10 billion light years from Earth. These galaxies are twice smaller than the elliptical galaxies today, but contain almost the same number of stars. Understanding how these galaxies have been able to grow so much, is one of the most pressing problems in astrophysics.

Let us imagine that we received the news of the birth of a baby that is 50 cm and weighs 80 kg. Most of us would think that it is a printing error. Well, that is what happened to astronomers when they found a type of galaxies in the distant universe with a very small size, but with a mass approximately 200 billion times the mass of our Sun. This mass can be compared to the mass of the most massive galaxies we observe around us.

Measurements of the superdense elliptical galaxies

If measurements are true, these galaxies would have densities between 10 to 100 times bigger than the density of the galaxies at maturity. Since this discovery, astronomers have tried to understand how these compact galaxies have been able to expand their sizes to reach the size of the galaxies that we observe in the universe.

As in the case of the baby, many researchers hesitated at the beginning of the measurements of the masses and sizes, made from deep images in different colors, therefore astronomers repeated these measurements to detect if it was an error in the determination.

However, an international team of astronomers from the Universidad Autónoma de Madrid, University of Florida, Universidad Complutense de Madrid, and the Instituto de Astrofísica de Canarias (IAC), decided to get a different measure: the velocity dispersion of its stars to distinguish the state of evolution of the compact galaxies. The velocity dispersion is a measurement of the speed with which stars move in relation to other stars, and it is a way to measure the density of galaxies. The smaller is the size of a galaxy with a given mass, faster have to move some stars in respect to other stars to compensate the effect of gravity and do not collapse.

The velocity dispersion measured by the team reveals not much higher values than the values measured in nearby galaxies. To understand this, it is necessary to consider that the velocity dispersion that we observe is caused by two components: the visible matter, and the invisible (dark matter). Both contribute to the total mass of the galaxy. In the past, the influence of the visible matter at the velocity dispersion was higher, because the light was more concentrated, but not the dark matter, and therefore the velocity dispersion has not changed much.

These results are fundamental to understand the causes of growth of these galaxies and favor a scenario in which these galaxies captured dwarf galaxies which are moved to occupy the outer part of the same, with little changing its central configuration. In this way, the size may increase by a factor of 2 while the velocity dispersion only increases by a factor of 0.8.

To perform these measurements, the research team has used the largest optical telescope in the world, the Gran Telescopio Canarias (GTC), meaning “Canaries Great Telescope“, with a diameter of 10 meters.

Ashley Stroupe, Staff Engineer at NASA’s JPL Robotics, says that “the most important aspect of the Mars Science Laboratory (MSL) is that, unlike other missions to Mars in which geologists could only tell us the rocks composition and if there was water, now go to develop studies in organic chemistry to find molecules or processes that are associated with the life”.

She also informs that, with the mission, be also observed many other aspects of the Martian environment to determine if it could have ever been habitable, bringing new approaches to the history of Mars.

Atlas V Lifts Off with MSL. Date: November 26, 2011. Credit: NASA.

The Mission’s scientific objective is to assess the habitability of a Mars region: know its potential as a habitat for the past or present life. To accomplish this, the mission’s Mars Science Laboratory (MSL) has just launched the rover Curiosity aboard a rocket ATLAS V.

The takeoff was carried from the Kennedy Space Center in Cape Canaveral, near Orlando, Florida (USA) on November 26, 2011. The spacecraft stages have been separated correctly according to the data received at stations such as the Diego Garcia Tracking Station in the Indian Ocean.

After a journey of 570 million kilometers, it is expected that the rover reaches its destination in August 2012. Those responsible for the mission have chosen as the landing point the crater Gale, about 100 km in diameter and with a central mound of 5 km in height. It is believed that in this area may be read much of the geological history of Mars. It is also believed that this area presents traces suggesting that it may have been a lake.

The specific objectives of the mission’s Mars Science Laboratory (MSL) are: to verify the biological potential of the area explored by the rover, investigate the planetary processes that happen on its surface and which influence its habitability (such as water, for example), and characterize the radiation levels reaching the surface of the planet Mars.

Essential instruments and specifications of rover Curiosity

Curiosity incorporates ten essential tools to carry out its mission. One of them is the environmental station REMS (Rover Environmental Monitoring Station), that will record pressure data, humidity, temperature, wind speed, and ultraviolet radiation.

Rover Curiosity weighs about 1,984 lb (900 kg) including 176 lb (80 kg) of scientific instruments. It is approximately the size of a small car equipped with six wheels. Its maximum speed will be 90 m (300 ft) per hour by automatic navigation, however, average traverse speeds will likely be about 30 m (98 ft) per hour. And it is designed to explore the red planet’s surface at least the duration of a Martian year (668 Martian sols or 686 Earth days).

APXS (Alpha-Particle-X-ray-Spectrometer) will determine the composition of rocks and the ground.

CHEMCAM (CHEMistry CAMera) is a spectrometer that will also analyze the Martian rocks.

CHEMIN (CHEmistry and MINeralogy) will quantify minerals and the chemical structure of rocks with X-Ray.

DAN (Dynamic Albedo of Neutrons) is a neutron detector that measures the amount of water through the detection of the number of hydrogen atoms there are in the ground.

MAHLI (MArs Hand Lens Imager) is a microscope to obtain images of rocks, surface, ice, and rime.

MARDI (MARs Descent Imager) will take high resolution images in color during the descent and landing on Mars to provide information about the geological context of the environment.

MASTCAM (MAST CAMera) is a set of two cameras that will provide multiple spectra and true color imaging at ranges of distance from few centimeters to several kilometres, and high definition video (10 pictures per second).

RAD (Radiation Assessment Detector) will characterize a wide range of radiation for possible human exploration of the planet.

SAM (Sample Analysis at Mars) will make mineralogical and atmospheric analysis. It can detect a wide range of biological components and analyse organic stable isotopes and noble gases.

REMS (Rover Environmental Monitoring Station), the rover station of environmental monitoring. REMS has been designed to record six atmospheric parameters: wind speed/direction, pressure, relative humidity, air temperature, ground temperature, and ultraviolet radiation.

MEDLI (MSL Entry Descent and Landing Instrument) will collect data during the entrance into the Martian atmosphere and landing, very valuable information to design the future missions to Mars.

Rover Curiosity works with radioactive source

This is the third generation of vehicles off-road that NASA sent to Mars. Its dimensions, power supplies, capabilities, and landing system, differentiate it from its predecessors. The two previous vehicles reached the Martian surface were protected by airbags and were fueled by solar panels, while rover Curiosity will climb down gently from the conveyor, which will carry it from the Earth, and will work with radioactive source.

The vehicle will send daily the data to satellites in orbit around Mars which, in turn, will redirect the data to Earth. The antennas of the NASA’s Deep Space Network will collect and send signals to Pasadena (California, USA).

From there the information will be distributed to different teams in the USA, Canada, Germany, France, Spain, and Russia. Scientists and engineers will work together to analyze all the data and decide every day the work that the rover Curiosity will perform the next day.

The constellation Ursa Major is also one of the largest. It is best known for a group of seven stars that form the so-called Plough. Five stars of the Plough are part of a group of very close stars among them. Usually the opposite happens, so the stars that belong to a same constellation are often in fact far distant from others. It has been able to discover this fact by measuring the distances that separate us from the stars and observing their own movements.

The constellation Ursa Major. Credit: Gerard Bajona

How to locate the constellation Ursa Major

Ursa Major serves as a starting point for finding other constellations. To locate this constellation just look to the North. The constellation Ursa Major covers a region of the sky between 73° N and 28° N declination, and between 8 hours 5 minutes and 13 hours 30 minutes of right ascension. This constellation is fully visible all year from latitudes higher than 62° N and part of the year from the area between 62° N and 17° S. Below 17° S, Ursa Major is never fully visible.

Remarkable stars in Ursa Major

The most interesting star in this constellation is Zeta Ursae Majoris (magnitude 2.5). This is a remarkable star system also called Mizar. This star actually consists of two stars: Mizar A (magnitude 2) and Mizar B (magnitude between 4 and 5).

Another particularly important star is Csi Ursae Majoris (magnitude 3.7), the first double star in which was discovered the gravitational attraction between the two components.

Mythology

According to a legend of the North American Indian populations, the stars of the Ursa Major represent two bears, four wolves and a hunting dog that accompanied the wolves in their raids. Wolves and dogs ventured into the sky to hunt the two bears who saw in the sky. Alcor, the little star next to Mizar, would be the hunting dog. The constellation Ursa Major has a position that represents the animal’s life cycle: rises in the spring at the end of lethargy, takes a complete turn by the sky and returns to sleep with the first cold.

The constellation Ursa Major chart

The constellation Ursa Major chart. Generated with Stellarium.

The constellation Ursa Major chart. Generated with Stellarium.

The Umbrella Galaxy NGC 4651.

The Umbrella Galaxy, NGC 4651 in Coma Berenices

The galaxy NGC 4651, also known as the Umbrella Galaxy, is located 35 million light years away, in the constellation Coma Berenices (Berenice’s Hair). Its diameter is about 50,000 light years, about half of the of the Milky Way. Its most striking feature is the huge stream of stars emanating from the galaxy and ending in a giant arch, a structure that is similar to an umbrella.

Moreover, the new image also reveals other minor arches, one of them visible on the right side of the image, which seems to be a sign that we are observing another umbrella hidden behind the disc of the galaxy. All of these brilliant fragments could belong to a huge symmetrical structure surrounding the galaxy, a huge galactic halo.

Galactic cannibalism

According to the well accepted theories on galaxy formation, most of the larger galaxies grow and evolve through the cannibalism of other smaller satellite galaxies. Computer simulations show that some of these dwarf galaxies, which are under the intense gravitational field of the central galaxy, can behave as a kind of yo-yo, approaching and moving away from the large spiral disc before being completely engulfed. During its trajectory, these galaxies suffer a great distortion of its own structure, scattering its remains along its orbit and disrupting the nearby regions of the outer spiral arms of the main galaxy.

The large spurts and arcs of stars observed in the galaxy NGC 4651 correspond to stellar debris of a dwarf galaxy which was entirely shattered due to gravitational tides caused by the large spiral, about some thousand million years ago.

A common phenomenon in the universe

The large spiral galaxies engulfing their dwarf neighbors are known since the early 1990′s. But almost all of the examples were restricted to the Local Group, which belongs the Milky Way. A group too small to verify, with statistical value, the predictions made by the theories of galaxy formation and evolution.

The exploration of a number high enough of galaxies may allow in a near future make quantitative tests of theoretical models of galaxies formation and evolution. These models predict a certain proportion of stellar streams of different shapes, sizes and types.

Ultra-Deep Image

The new image of the Umbrella Galaxy, the NGC 4651, is obtained by an international team of astronomers led by Martínez-Delgado in collaboration with the amateur astrophotographer R. Jay Gabany and researchers from the University of California, Santa Cruz. It is a combination of many observations in monochrome with the large Japanese Subaru Telescope of 8.3 m in diameter located at 4,100 m altitude at Mauna Kea (Hawaii), with other data obtained by Gabany’s Telescope of 0.5 m at the Blackbird Observatory.

This work shows how the collaboration between professional and amateur astronomers often leads to powerful results. Astronomy is one of the few Sciences where the amateur work has contributed to scientific results of first-line throughout the history. For example, the discoveries of Uranus and Pluto were made by astronomers who were amateur astronomers when they made its discoveries.

This artist's concept shows a broken-up asteroid. Image credit: NASA/JPL-Caltech.

New data collected by the NASA’s WISE Space Telescope (Wide-field Infrared Survey Explorer) seem to discard the theory that pointed to a particular family of asteroids as responsible for the disappearance of the dinosaurs; as was published one year ago in the Journal Geology: «Dinosaurs disappeared from the face of the Earth 65 million years ago by the impact of at least two meteorites.»

“After the investigation of the scientific team of the WISE, the disappearance of the dinosaurs remains an unresolved case”, Lindley Neil Johnson said, the manager of NASA’s Near-Earth Object (NEO) Observation Program in Washington, D.C.

The theory, proposed in 2007, defends that 160 million years ago, an asteroid named Baptistina collided against another asteroid of the main-belt Mars and Jupiter. After the impact, huge fragments spread and one of them ended impacting against the Earth and caused the extinction of the dinosaurs.

“With infrared light, the WISE has been able to make some more precise calculations and has put into question the temporary data about the theory of the Baptistina family.” With the initial calculations made with visible light, scientists estimated the size and age of the members of the Baptistina family. “We now know that these calculations were not accurate,” Johnson says.

The question raised now by astronomers is the origin of this asteroid, the family which this asteroid belongs and how ended on Earth. “We are working on a tree with asteroid families,” Joseph Masiero said, lead author of the study.

“65 million years ago, the fragments formed after the collision did not have time to travel to a resonance zone where the gravity of Jupiter and Saturn would have shot them towards the Earth,” Amy Mainzer says, co-author of the study.

Size and reflectivity

The observations by WISE detect the infrared light from the asteroid which, in turn, is related to its temperature and size. Once the size is known, the reflectivity of the object can be recalculated by combining data from infrared light with previous data from visible light. It is difficult to establish precisely its size without knowing the reflectivity.

For the study, the NEOWISE team measured the reflectivity and the size of about 120,000 main-belt asteroids, included 1,056 members of the Baptistina family. The scientists calculated that the original ancestor of this family broke out about 80 million years, half of what was initially raised.

The new findings have revealed that a fragment of the original asteroid of the Baptistina family needed less time to collide with the Earth of what originally was thought.

William Herschel.

Herschel began to calculate, design and build their own telescopes. Less than a year after having bought the Ferguson’s book, Herschel estimated and polished the most perfect and powerful mirrors around the world, because he understood immediately that the future depended on the reflecting telescopes.

He was building the instruments and observing the sky at the same time. As early as February 1774 he had already observed the Orion Nebula, discovered in 1610.

On March 13, 1781 Herschel noted an unregistered object at first glance, that looked like a comet: by studying this object carefully soon managed to determine that it was actually a new planet, Uranus.

Herschel had discovered the planet Uranus by testing his newly built reflecting telescope, of seven foot long, six inch diameter, ƒ14. He had pointed it to the constellation of Gemini and observed a star which was not supposed to be there. The object shone with a yellow color and moved slowly.

Herschel observed the object every night and came to the conclusion that he had discovered the seventh planet in the Solar System. He asked other astronomers to confirm the diagnosis, and all agreed with him: a new planet was located to twice the distance of Saturn.

In 1783, Herschel discovered that the Sun was not quiet as he had always believed. He showed that our Sun is moving and dragging the Solar System towards the star Lambda Herculis. He named the point where this movement is directed as “solar apex”. Four years later, on January 11, 1787, he discovered two moons of Uranus: Titania and Oberon.

In 1788, William Herschel married the widow Mary Baldwin Pitt, who had been married to the powerful London merchant John Pitt. Lady Pitt had lost her first husband two years before she met Herschel. William Herschel and Mary had one child, John Herschel, born at Observatory House on March 7, 1792.

William spent two years building a large telescope, and finished in 1789, with an aperture of 1.2 m. So he pointed the telescope to the night sky for the first time on August 28 and discovered the sixth Moon of Saturn, Enceladus, in few minutes. On September 17 he descovered the seventh Moon, Mimas, which gives an idea of the outstanding optical quality of that enormous instrument. This telescope was the largest telescope in the world for over fifty years, to be defeated only by the “Leviathan” of Lord Rosse, who had a mirror of 1.98 m in diameter.

William Herschel also discovered planets, moons, comets and more than 2,500 galaxies and nebulae, and realized that the Sun takes us towards Hercules.

He studied the movement of stars, designed a very correct model of the Milky Way on the basis of their statistics of populations of stars in each sector of the sky, showed ideas about the nature of nebulae, and filed a primitive theory of “Island Universes” (galaxies) which had been advanced by the philosopher Immanuel Kant.

William Herschel died on August 25, 1822 at his home in Slough, at the advanced age of 84. As a curious fact should be noted that the planet discovered, Uranus takes 84 years to its orbital period, so Herschel was born and died when Uranus was in the same position.

The Milky Way. Credit: Gerard Bajona.

The Milky Way: In the northern hemisphere

In the northern hemisphere the best period to see the Milky Way is in August. The center of the Milky Way is in the early hours of the night over the observer’s head, but in January can only see the less bright part, which is opposite to the center.

The Milky Way: In the southern hemisphere

For people in the southern hemisphere, the best months to observe the Milky Way are also in July and August, when the center of the galaxy is located high in the sky, in the constellation of Sagittarius. During the first part of the year you can see the darker regions of the constellations of Vela and Popa, where the Milky Way is less spectacular.

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Map of the Milky Way, by Herschel.

The image shown is flipped 180 degrees on the horizontal axis from the original, as first published in the Philosophical Transactions of the Royal Society in 1785; the bifurcated arms of the illustration should be on the left.

By using a 18.7-inch aperture telescope (47 cm), Herschel counted the stars of the Milky Way in all directions of the sky. In some directions, he discovered a single star per unit of visual field. In others, however, he observed 500. Based on the assumption that the stars were equally distributed in all directions, Herschel drew an outline of the Milky Way that showed its flattened structure. He placed the Sun near the centre of the map, the brighter spot.

With his sister Caroline, William also created an extensive catalog of nebulae using the then enormous 40 foot telescope in the garden of his house, in England.

In 1783, Herschel discovered that the Sun was not quiet as he had always believed: by comparing the observations of several fixed stars, he showed that our Sun is moving and dragging the Earth and the rest of his planetary entourage, towards the star Lambda Herculis. He also named the point where this movement is directed as “solar apex”.

Four years later, he discovered Titania and Oberon, two moons of Uranus.

An artist's rendering of the Kepler-16 system, showing the binary star being orbited by Kepler-16b. Credit: NASA / JPL-CALTECH.

The astronomers had already several candidates of planets orbiting two stars, but so far not been able to observe the evidence of its existence.

“Kepler-16b is the first example of circumbinary planet – that orbits two stars instead of one-. Once again we have verified that our Solar system is just one example of the wide variety of planetary systems that nature can create,” Josh Carter said, researcher at the Harvard-Smithsonian Center for Astrophysics, and one of the authors of this study.

The journal Science published this week the details of the discovery, announced by NASA in a press conference. The study is led by Laurance R. Doyle, researcher at the Carl Sagan Center for the Study of Life in the Universe.

The Kepler-16b characteristics

The planet is in the constellation Cygnus, in the star Kepler-16. The Kepler-16b orbit coincides exactly with the plane of the orbit of the binary star system, and this is visible from Earth, so it is possible to observe multiple eclipses in this system. The planet’s orbit around its suns lasts 229 days.

The mass and size of the planet are similar to Saturn’s. Its stars are cooler than our Sun, smaller (20% and 60%, respectively, less mass) and are located at a distance of 200 light years from Earth.

Kepler space telescope, launched in 2009 with the aim of searching for Earth-like objects, has captured more than 1,200 planets. The sophisticated NASA probe is able to observe the brightness of stars more than 155,000.

Theoretical scenario of a galaxy forming stars. Credits: ESA–AOES Medialab

This space telescope into orbit since 2009, has allowed to discover a process of evolution that scientists of the project considered “much more stately.” The discovery was made possible by the observations made in two regions of the sky, each one of a size equivalent to one-third of the full moon. ESA says in a statement that gas is the element which establishes the birth of a star, instead of the galaxies collision.

“Herschel has been studied more than a thousand galaxies more distant covering the 80% of the cosmic history,” indicates ESA in its statement, which said it has been like “look the history of the universe through a lock hole.”

It was already known that the rate of star formation experienced a large peak in the early stages of the universe, about 10 billion years, when some galaxies originated stars at a rate of ten to a hundred times greater than what can be seen today.

In the current universe, according to the ESA, these rates are unusual, and always seemed to be related to a collision between galaxies, so scientists assumed that it had always been the case.

Forming stars at a fast rate

ESA explains that in studying very distant galaxies whose light began to ride the sky for thousands of millions of years, the Herschel telescope has been shown that this assumption was wrong.

The analysis of the data generated has made it possible to conclude that “the collisions between galaxies only played a small role in the evolution of the early universe, although that some of the youngest galaxies were forming stars at a fast rate.”

To compare the amount of infrared radiation emitted by these galaxies at different wavelengths, the research team was able to demonstrate that the rate depends only on the amount of gas stored in the galaxy, regardless of collisions that are suffering.

“The gas is the raw material for the formation of new stars. (…) If the galaxy contains more gas, more stars are formed,” says the release.

One of the researchers involved, David Elbaz, says that:

“Collisions only play a decisive role in those galaxies that still not hold a large amount of gas, providing the necessary material to trigger high rates of star formation.”

According to the ESA, that’s what you can see in the current galaxies, which after having been creating stars for more than 10 thousand millions of years, have exhausted most of its gas reserves.

“These new observations now change our perception of the history of the Universe,” congratulate themselves at the European Space Agency, according to which this explanation “much more stately” establishes that “most of the galaxies are growing slowly and naturally from the gas they attract from their surroundings.”