Bibcode
González Pérez, J. M.; Metcalfe, T. S.
Bibliographical reference
Astronomy and Astrophysics, Volume 493, Issue 3, 2009, pp.1067-1073
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2009
Journal
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Description
Aims: We present a new method that investigates the evolutionary history
of the pulsating DB white dwarf GD 358 using
asteroseismology. This is done considering the internal C/O profile,
which describes the relative abundances of carbon and oxygen from the
core of the star to its surface. Different evolutionary channels lead to
the generation of different C/O profiles, and these affect the pulsation
periods. Methods: We used the C/O profiles associated with white
dwarfs that evolved through binary evolution channels where the
progenitor experienced one or two episodes of mass loss during one or
two common envelope (CE) phases, and two profiles from single-star
evolution. We computed models using these different profiles and used a
genetic algorithm (GA) to optimize the search in the parameter space for
the best fit to the observed pulsation periods. We used three-parameter
models, adjusting the stellar mass (Mstar), the effective
temperature (T_eff), and the helium mass of the external layer (M_He).
Results: Our results suggest that binary evolution profiles may
provide a better match to the pulsation periods of GD 358. The best fit
to the observations is obtained using a profile related to an
evolutionary history where two episodes of mass loss happen during two
CE phases, the first during the RGB (red giant branch) stage. The values
obtained are T_eff = 24300 K, Mstar = 0.585
M&sun;, and log (M_He/Mstar) = -5.66. The best-fit
model has a mass close to the mean mass for DB white dwarfs found in
various works and a temperature consistent with UV spectra obtained with
the IUE satellite.
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