GEPI

Yannick Boissel

Newly doctor, I defended my thesis on December 13th, 2010, performed at LESIA, on a topic combining planetary and stellar physics:
exploring the far reaches of our solar system with stellar occultations.

I’m leaving today to explore the Galaxy in the Stellar and Galactic Physics team, as a Post-doc. I work on the project
RTIGE real-time 3D simulation of our Galaxy, its structures and
objects which it is populated. This work has an educational and scientific purpose: fruits of this work will be used as part of popularization to the general public, education and
conferences of researchers. Many of the methods I will develop may also be used by Gaia, and Gaia data will enrich these simulations.

Paola Di Matteo

When I was asked to introduce myself to update the page for newcomers to GEPI, I smiled.
It is not easy to introduce to people we already know for several years. But GEPI is a big laboratory, after 3 years spent here I have not finished to know all the people who work there, so here’s a quick summary of my life, for those who do not know it yet.

I was born in Rome, some years ago, where I did all my studies: Bachelor’s degree in classics, a master’s degree in mathematics and a doctorate in astronomy. I defended my thesis in 2005 at the University of Rome La Sapienza, supervised by Roberto Capuzzo Dolcetta. It is said that we never forget our first love and that is the case for me with my thesis: the study of globular clusters in the galactic tidal field. Using N-body simulations, I studied the formation, morphology and kinematic properties of tidal tails that are formed around clusters in orbit around the host galaxy. During my PhD, the first spectacular tidal tails around galaxy clusters were being discovered (here is a press release from the discovery of tidal tails around Palomar 5). These results have contributed greatly to my enthusiasm for the subject.

After my PhD, I arrived in France, with a postdoctoral fellowship at LERMA, Observatoire de Paris, to work with Francoise Combes and colleagues on a project completely new for me at the time: the study of mergers and interactions of galaxies. The project, supposed to last one year, is still in progress! Over the years at LERMA, and then at GEPI with Matthew Lehnert, I made a thousand of N-body simulations of interacting galaxies (for those who are interested, see the Project Galmer, which I am PI). These simulations allowed us to learn much about the evolution of galaxies during an interaction with a companion: starburts, evolution of metal content, redistribution of angular momentum, etc. ...
These processes also affect our Galaxy, and we want to understand how its different components (bulge, thin disk, thick disk, halo(s)) are structured and how each of these processes has helped to shape the properties that are observed today.
Again, computer simulations are a key asset for discriminating between different evolutionary scenarios and interpret the observations. That is the aim of my new postdoc, who has just started in the team Stellar and Galactic Physics at GEPI, which is funded by ANR GalHis (PI: Annie Robin, Observatoire de Besançon). In collaboration with Frédéric Arenou, Carine Babusiaux, Ana Gómez, Misha Haywood, David Katz and Frédéric Royer, I work in modeling the structure of the Milky Way, with eyes pointed at Gaia, which will soon revolutionize our understanding of the galaxy we live in.

Panagiotis Gavras (Παναγιώτης Γαβράς)

As a child I always spent my summer holidays at a very small village, beyond light pollution, in a Cyclades island (Greece). So I developed my passion in astronomy and at the age of 10 I knew what I wanted to do with my life. After a degree in physics and Master in Astronomy at the University of Athens, I decided to chase a career in Astronomy. Thus, after fulfilling my military service, I started my PhD at the National Observatory of Athens and the University of Athens with Dr. Dimitri Sinachopoulos as my supervisor.

My thesis topic was about visual binaries with very long period, such as the common proper motion binaries. I tried to answer questions like: why we know so few of them, can we improve the identification process. I also performed CCD observations of visual double stars. Parallel to my thesis obtained in December 2010, I worked for Gaia where I was member of Development Unit 470 (part of Coordination Unit 4), which studies the extended objects of Gaia.

So here I am in Paris with my first professional contract to work with Frédéric Arenou for Development Unit 439, the non-single star solution combiner. My job here is to continue the development of the software that combines the solutions coming from other DUs.

Rosine Lallement

I am the "senior" among the group of newcomers. After many years in Service d’Aéronomie (now LATMOS), a laboratory dedicated mainly to terrestrial and planetary atmospheres, I wanted to join a "100% astrophysics" laboratory. In LATMOS I worked on the interface between the Sun and its gaseous galactic environment.
I have always associated the heliospheric component of my work with the analysis of space observation data, and the local interstellar medium component — with scales ranging from 1 to a few hundred parsecs — with ground and space observations. The first component was therefore about the solar wind, the galactic gas in the heliosphere and the mixed species derived from their interaction.

This is the second part — the study of the interstellar medium, its physics and its 3D structure, but this time on a larger scale — that I wish to continue in GEPI. For that, the Gaia mission seems an important and very promising step, and I thought the best way forward was to be part of the Gaia team itself, combining aspects of stellar and interstellar spectroscopy. My hope is that the three-dimensional interstellar medium becomes a topic of GEPI studies in support of the study of the Galaxy and the results of Gaia, to possibly include in the future the interactions star-galactic gas.

Séverine Raimond

Since I was a child, I have been passionate about astronomy and observing the night sky. I worked in animation in astronomy, especially for "La Ferme des Étoiles". But my real dream is to work in research in astrophysics.

After my Master degree in Astronomy/Astrophysics at the Observatoire de Strasbourg, I started a PhD at LATMOS (Laboratory Atmospheres, Media and Space Observations) supervised by Rosine Lallement. I am currently in my third year and I followed Rosine who joined GEPI earlier this year.

The subject of my thesis is the local interstellar medium, local meaning within a radius of 300 pc around the Sun! By analyzing the interstellar absorption lines in a stellar spectrum, we can determine a certain amount of information on clouds present on the line of sight to the star observed (the amount of absorbent on the line of sight, velocity, temperature of the cloud). By observing a large number of spectra and using an inversion program, it is then possible to reconstruct the gas distribution in 3 dimensions. It is important to process the most spectra possible because the more lines of sight, the better the mesh. Thus the analysis of interstellar lines of NaI doublet (resp. CaII) allowed the construction of a data cube of the neutral gas (resp. ionized) around the Sun, revealing a low density gas cavity called the "Local Bubble". Our Sun is "embedded" in this cavity which extends over a radius of about 200 pc and is surrounded by large, dense clouds.

Lilia Solovyeva (Лилия Соловьева)

As far as I remember, I always wanted to understand our universe, the processes around us and engineering that allows us to study and improve our lives. That’s why I made my studies at the State University of St. Petersburg, Faculty of Physics, studying science for engineers on the topic Earth and Space. Space physics is well developed in Russia, there were lots of interesting missions and I always had interest in this field. That is why during my studies, I conducted several courses on the analysis and processing of satellite data (Cluster, SOHO, TOMS) on the physics related to solar-terrestrial interaction.

Eventually I wanted to obtain educational experience in another country, I chose France because of the many relations between Russia and France. I have completed the engineering cycle at the Ecole Polytechnique in Palaiseau, as part of the International Program. After that I started my professional experiences in France, in CEA (Commissariat à l’Energie Atomique) where I prepared my PhD (supervised by Romain Teyssier and Jean-Luc Sauvageot). As part of this work, I developed the data processing and analysis chain for XMM-Newton (images and spectra) and numerical simulations. I studied objects in the Universe such as galaxy clusters, their nature and physics using X-ray, visible and radio data. I participated in several projects for international collaboration on this topic.

I got my PhD at the University Paris 7 in 2009. Working as a research engineer at CEA, I decided to go this route. That is why I then started working at the Laboratory of Dynamic Meteorology (Paris 7 and Ecole Polytechnique) as an engineer R&D for the ExoMars mission, in particular I reduced and analyzed the data of numerical simulations of the atmosphere of Mars.

In 2010 I started my work in GEPI for the future mission Gaia (satellite prepared by ESA, launch scheduled for late 2012) in the group "Coordination Unit 6" with David Katz. CU6 prepares the spectroscopic data processing chain in collaboration with CNES, and Mullard Space Science Laboratory. I work as a research engineer, I participate in the coordination between institutes, scientific and technical choices, follow-up work, analysis and preparation of documentation and test development.