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The Instability Strip of ZZ Ceti White Dwarfs
Van Grootel, Valérie; Fontaine, G.; Brassard, P. et al.
2015In Astronomical Society of the Pacific Conference Series, 493, p. 211
 

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Abstract :
[en] The determination of the location of the theoretical ZZ Ceti instability strip in the log g − Teff diagram has remained a challenge over the years, due to the lack of a suitable treatment for convection in these stars. We report here a detailed stability survey over the whole ZZ Ceti regime, including the low and extremely low masses. We computed to this aim 29 evolutionary sequences of DA models with various masses, chemical layering, and core compositions. These models are characterized by the so- called ML2/α=1.0 convective efficiency and take into account the important feedback effect of convection on the atmospheric structure. We computed pulsation spectra for these models with the Liège nonadiabatic pulsation code MAD, which is the only one to conveniently incorporate a full time-dependent convection treatment and, thus, provides the best available description of the blue edge of the instability strip. On the other hand, given the failure of all nonadiabatic codes to account properly for the red edge of the strip, including MAD, we tested the idea that the red edge is due to energy leakage through the atmosphere. Using this approach, we found that our theoretical ZZ Ceti instability strip accounts remarkably well for the boundaries of the empirical strip.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Van Grootel, Valérie  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie
Fontaine, G.
Brassard, P.
Dupret, Marc-Antoine ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie
Language :
English
Title :
The Instability Strip of ZZ Ceti White Dwarfs
Publication date :
June 2015
Event name :
19th European Workshop on White Dwarfs
Event organizer :
P. Dufour & P. Bergeron
Event place :
Montréal, Canada
Event date :
11-15 août 2014
Audience :
International
Journal title :
Astronomical Society of the Pacific Conference Series
ISSN :
1050-3390
Publisher :
Astronomical Society of the Pacific, San Francisco, United States - California
Volume :
493
Pages :
211
Funders :
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE]
Available on ORBi :
since 29 September 2014

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