Radiative levitation: a likely explanation for pulsations in the unique hot O subdwarf star SDSS J1600+0748 - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue Communications in Asteroseismology Année : 2008

Radiative levitation: a likely explanation for pulsations in the unique hot O subdwarf star SDSS J1600+0748

Résumé

SDSS J1600+0748 is the only hot sdO star for which unambiguous multiperiodic luminosity variations have been reported so far. These rapid variations, with periods ranging from 60 s to 120 s, are best explained qualitatively in terms of pulsational instabilities, but the exact nature of the driving mechanism remains a puzzle. Models with uniform metallicity are unable to excite pulsation modes in the range of interest as demonstrated most eloquently by Cristina Rodŕıguez-Ĺ opez in her Ph.D. thesis at the Universidad de Vigo in 2007. We confirm her results here, but also show that the inclusion of radiative levitation in the equilibrium models changes the picture dramatically. We find indeed that p-mode pulsations with periods overlapping with the observed ones in SDSS J1600+0748 can be excited in models in which radiative levitation of iron is taken into account. This process provides the necessary boost to the opacity driving mechanism. We conclude that radiative levitation apparently is an essential ingredient of the excitation physics at work in this unique star.
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Dates et versions

hal-00391915 , version 1 (05-06-2009)

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G. Fontaine, P. Brassard, E. M. Green, P. Chayer, S. Charpinet. Radiative levitation: a likely explanation for pulsations in the unique hot O subdwarf star SDSS J1600+0748. Communications in Asteroseismology, 2008, 157, pp.305-306. ⟨hal-00391915⟩
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