May 9, 2020 – Stellar Seismology

Mathieu Vrard received his undergraduate degree at the University of Versailles-Saint-Quentin (UVSQ) and his graduate degree at Paris Observatory (Observatoire de Paris). He defended his PhD in 2015. After, he spent three years at the Centro de Astrofisica e Ciencias do Espaco (CAUP) at Porto in Portugal. He is currently working as a stellar seismologist at the Ohio State University.

Talk Summary: In the first half of the twentieth century, the base of stellar physics was already well understood but the physicist were quite pessimistic about the knowledge that could ever be acquired on the interior of stars. It is indeed impossible to obtain direct observations on the star’s interiors through their light emission since it comes from their surface. But, of course with time, a better understanding of the physics of the stars brought new observational techniques. In this presentation, I will talk about a technique that was discovered in the second half of the twentieth century and that allows to obtain precise information on the stellar structure with the observation of the waves going through the stars. Waves are indeed propagating into stars and produce tiny variations of the observed stellar parameters (luminosity, radius,…) that can be retrieved. With this, it is possible to have precise information on the waves and, therefore, on the medium they propagate into, here the interior of the stars. I will talk about the basic principles of that method and its origins before showing a few modern of its applications.

A recording of Mathieu’s talk can bee found on the CAS YouTube page: https://www.youtube.com/watch?v=bgVvXdz9sHQ&t=2526s