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The contribution of asteroseismology to a better understanding of helium-core-burning sdB stars

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posted on 06.01.2020 by Charpinet, Stéphane, Brassard, Pierre, Fontaine, Gilles, Van Grootel, Valérie, Zong, Weikai, Randall, Suzanna, Green, Elizabeth

SdB stars are evolved compact objects of about half a solar mass burning helium in their core. Some develop nonradial oscillations driven by a kappa mechanism powered by the accumulation of iron and nickel in their envelope through the selective action of radiative levitation. They come into two main flavors that show rapid p-mode oscillations on a timescale of minutes (the V361 Hya class) or g-modes with periods of 1-4 hours (the V1093 Her class). These pulsations have been particularly propitious to the development of detailed asteroseismic investigations of the internal properties and fundamental parameters of these stars. Here, I review the contibution of asteroseismology to a better understanding of sdB stars, regarding in particular their link to stellar evolution. I also discuss their potential to constrain important processes that occur in the deep interior of helium core burning stars and that ultimately shape the structure of white dwarfs.