4/16/2023 0 Comments Kepler space telescope![]() Searching for seismic solutions that do not depend on stellar evolution calculations is a key requirement of this strategy. The outcome is a full seismic model of the pulsating white-dwarf star under consideration, including its internal core and envelope chemical stratification. The method is meant to reduce as much as possible solution dependency relative to stellar evolution uncertainties. Our approach involves new models incorporating flexible internal profiles for the main chemical constituents (H, He, C, and O) that are optimized, along with other fundamental parameters (T eff and log g), to determine the stellar structure that best reproduces the observed period spectrum of a given star. ![]() Here, we review the most recent efforts from our group to perform a complete seismic cartography of white-dwarf interiors. ![]() From these early days on, many approaches have been attempted to fully exploit this potential, with various levels of success. It was swiftly recognized that white-dwarf pulsators could offer new opportunities to unravel their inner structure and dynamics from the observed low-degree, low-order gravity (g-)modes. Probing internal properties of white-dwarf stars has been amongst the earliest objectives of asteroseismology, following the first discovery in the late 1960s of non-radial pulsations in these evolved compact stars. Learning about the internal structure of WDs place important constraints on the WD cooling sequence and our overall understanding of stellar evolution for low mass stars. In this paper, we describe our approach to WD asteroseismology using WDEC models and we present seismological studies for 29 observed DAVs in the Kepler and K2 datasets, 25 of which have never been analyzed using these observations, and 19 of which have never been seismically analyzed in any capacity before. We used the White Dwarf Evolution Code (WDEC) to calculate a grid of over one million models with various temperature, stellar mass and mass of helium and hydrogen layers, and calculated their theoretical pulsation periods. Using differential photometry to produce light curves, we can determine the observed periods of pulsation from the WD. As these stars cool, they reach temperatures and conditions that cause the stars to pulsate. In this evolutionary stage, WDs enter the cooling sequence, where the stars radiate away their thermal energy, and are basically cooling. All single stars that are born with masses up to 8.5 - 10 $M_\odot$ will end their lives as a white dwarf (WD) star. ![]()
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