Good Vibrations Seminar #5: Martin Farnir (STAR institute, Liège University)

March 10, 2021 | 10:00 am 11:00 am
CET, Liege, Belgium

Low mass stars seismology with WhoSGlAd and EGGMiMoSA

Martin Farnir (STAR Institute, Liège University)

Since most of the information we receive from outer space is carried by stellar light, it comes as a necessity to properly characterise them. With the advent of space missions, it becomes possible to do so, thanks to the gathering of data of unprecedented quality. The past CoRoT and Kepler missions provided the stellar scientists with a wealth of data such that it allowed for the asteroseismology, the study of stellar pulsations and their link with the stellar structure, to thrive. This enabled to provide a detailed characterisation of distant solar-like stars and to pinpoint the shortcomings of current models. However, to provide precise inferences from observed oscillation spectra, it is necessary to have methods which are able to take the most advantage of the exquisite precision of the data. Both of the methods I develop are tailor-made for such needs. The first method, WhoSGlAd, accounts for the oscillations of main-sequence solar-like stars and the acoustic glitches they may exhibit. Acoustic glitches are an oscillating feature in the spectrum caused by a sharp feature in the stellar structure. The adjustment is done in such a way that the fitting parameters are completely independent and the computations are extremely fast. The parameters are then combined to build seismic indicators relevant of the stellar structure as little correlated as possible. Those are then used as constraints to stellar models. The second method, EGGMiMoSA, aims at providing a precise adjustment of the complex behaviour displayed by the mixed-modes oscillation spectra of sugbiant and red giant stars. Mixed-modes constitute a unique opportunity to probe the stellar interior from the surface to the core of the star. Again, the objective of the method is to define seismic indicators relevant of the stellar structure in order to constrain stellar models. During the present seminar, I will introduce both techniques and several results obtained via their use.

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