Abstract:

What is the Solar System made of? How did the Solar System evolve? One way to investigate these fundamental questions is through the study of meteorites. Many meteorites display isotope anomalies that have been attributed to the heterogeneous distribution of star dust in the protoplanetary disk. Active research is directed at documenting the stars from which the dust originated, the composition of the dust, and the process(es) that led to its heterogeneous distribution in the disk. Understanding these features would permit the identification of the stellar building blocks of the Solar System and place observationally derived constraints on processes of disk dynamics which influenced planet formation. In the present study, the identity of the stellar events and the chemistry of the dust are investigated and interpreted in the context of recent nucleosynthesis models.

Short bio:

My research interests lie in using the distribution of isotopes in meteorites and terrestrial materials to constrain the early Solar System evolution and the building blocks of the Earth and Moon. I use a combination of high precision cosmochemical isotope data and astrophysical modelling to constrain the different stellar contributors to the early Solar System and how these components were mixed into the early disk.

Abstract:

Cosmic rays are high-energy particles – mostly protons and atomic nuclei – observed arriving at Earth from outside the solar system. They can reach ‘ultra-high’ energies of up to 10^20 eV, but the search for the cosmic accelerators producing them is still ongoing. Candidates include supermassive accreting black holes, and the supernovae of the most massive stars.

One method to detect them is the “lunar technique”, by which radio telescopes observe the Moon and search for the nanosecond flashes of radio waves emitted when these particles interact. Critical to this technique is understanding the properties of the lunar surface and sub-surface, and how this affects particle interactions and the transmission of the emitted radio waves.

This talk will briefly review the status of ultra-high-energy cosmic ray research, and past observations with the lunar technique. The focus will be on current uncertainties in modelling the lunar (sub-)surface, and how this affects the outgoing radio signal. The talk will conclude with the prospects for using this technique with the Square Kilometre Array to discover the origin of the highest-energy cosmic rays.

Short bio:

Clancy did his PhD at University of Adelaide 2006-2009 on lunar detection of neutrinos, for which he was awarded the 2010 Bragg Gold medal. He then held post-doc positions in Nijmegen (the Netherlands) working on the LOFAR radio telescope (2009-2011) and in Erlangen (Germany) working on ANTARES and KM3NeT neutrino telescopes (2011-2017). Clancy is currently at Curtin Institute of Radio Astronomy to work on fast radio burst detection.

Abstract:

One of the important steps in the prediction of an impact threat to Earth raised by potentially hazardous asteroids is the understanding and modeling of the processes accompanying the object’s entry into the terrestrial atmosphere. Such knowledge enables characterization, simulation and classification of possible impact consequences. For observed meteor events the reconstructed atmospheric trajectory is the key to deriving the pre-impact meteoroid’s orbit in the Solar System on one hand, while on the other hand, it is also required for dark flight simulations which enables us to locate surviving meteorite fragments on the ground. Using dimensionless expressions, which involve the pre-atmospheric meteoroid parameters, we have built physically based parametrisation to describe the changes in mass, height, velocity and luminosity of the object along its atmospheric path. The developed model is suitable to estimate a number of crucial unknown values including the shape change coefficient, ablation rate, and surviving meteorite mass. It is also applicable in the  prediction of the terminal height of the luminous portion of flight and therefore, the duration of the fireball. Besides the model description, we demonstrate its application using the wide range of observational data from meteorite-producing fireballs appearing annually (such as e.g. the Annama, Košice, Neuschwanstein and Osceola fireballs) to larger scale impacts (such as the Chelyabinsk, Sikhote-Alin and Tunguska event). In particular, this approach enabled us to successfully recover the Annama meteorite based on the analysis of the fireball observed by the Finnish Fireball Network on 19 April 2014.

Short bio:

 Maria Gritsevich is a Senior Scientist at the Department of Physics, University of Helsinki (UH), currently working for the ERC Advanced project SAEMPL (Scattering and absorption of electromagnetic waves in particulate media). She has also worked as a research fellow at the European Space Agency, and as a Specialist Research Scientist at the Finnish Geospatial Research Institute. She received the International Academic Publishing Company “Nauka/Interperiodica” and the Pleiades Publishing Inc. best journal publication in Physics and Mathematics award in 2009 and was awarded the Gold Medal for young scientists from the Russian Academy of Sciences in 2010.