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An Asteroseismological Analysis of the Pulsating B Subdwarf Feige 48 Taking into Account Rotation
Van Grootel, Valérie; Charpinet, Stéphane; Fontaine, Gilles et al.
2008In Leaflet - Astronomical Society of the Pacific, 392, p. 317
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Abstract :
[en] We present a new analysis of the short period pulsating sdB star Feige 48 using the same observations as done in our previous work, but exploiting, this time, our new period-matching codes that include the rotation of the star. The pulsation spectrum of Feige 48 shows the signature of rotational splitting with a mean frequency spacing of about 28 μHz between the components of three different frequency multiplets. In addition, Feige 48 has been shown to be a member of a close binary system with an invisible (most likely a white dwarf) companion. Assuming various internal rotation laws, we are now able to fit all nine observed frequencies simultaneously, and not only the four m = 0 components that we identified a priori in our previous effort. For solid body rotation, our optimal model shows slightly different structural parameters than those obtained previously on the basis of purely spherical models. Interestingly, that optimal model is also characterized by a rotation period of 9.028 h, which falls exactly on the value of the orbital period found independently from spectroscopy, namely, 9.024 ± 0.072 h. This very strongly implies that Feige 48 is tidally locked, a suggestion quite consistent with theoretical expectations for such a close binary system. In the same vein, our investigations also demonstrate explicitly that the idea of a fast rotating core can be eliminated for Feige 48.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Van Grootel, Valérie  ;  Université de Toulouse/Université de Montréal (UdeM)
Charpinet, Stéphane;  Laboratoire d'Astrophysique de Toulouse-Tarbes (LATT)
Fontaine, Gilles;  Université de Montréal - UdeM
Brassard, Pierre;  Université de Montréal - UdeM
Green, Elizabeth M.;  University of Arizona
Chayer, Pierre;  Johns Hopkins University > Bloomberg Center for Physics and Astronomy
Language :
English
Title :
An Asteroseismological Analysis of the Pulsating B Subdwarf Feige 48 Taking into Account Rotation
Publication date :
January 2008
Event name :
Third meeting on hot B subdwarfs and related objects
Event organizer :
Dr. Karl Remeis-Sternwarte, Bamberg
Event place :
Bamberg, Germany
Event date :
du 23 au 27 juillet 2007
Audience :
International
Journal title :
Leaflet - Astronomical Society of the Pacific
ISSN :
0004-6272
Publisher :
Astronomical Society of the Pacific, San Francisco, United States - California
Volume :
392
Pages :
317
Peer reviewed :
Peer reviewed
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since 23 January 2012

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