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Article Dans Une Revue Monthly Notices of the Royal Astronomical Society Année : 2007

An asteroseismic study of the beta Cephei star theta Ophiuchi: constraints on global stellar parameters and core overshooting

Résumé

We present a seismic study of the beta Cephei star theta Ophiuchi. Our analysis is based on the observation of one radial mode, one rotationally split l = 1 triplet and three components of a rotationally split l = 2 quintuplet for which the m values were well identified by spectroscopy. We identify the radial mode as fundamental, the triplet as p1 and the quintuplet as g1. Our non-local thermodynamic equilibrium abundance analysis results in a metallicity and CNO abundances in full agreement with the most recent updated solar values. With X ∈ [0.71, 0.7211] and Z ∈ [0.009, 0.015], and using the Asplund et al. mixture but with a Ne abundance about 0.3 dex larger, the matching of the three independent modes enables us to deduce constrained ranges for the mass (M = 8.2 +/- 0.3Msolar) and central hydrogen abundance (Xc = 0.38 +/- 0.02) of theta Oph and to prove the occurrence of core overshooting (alphaov = 0.44 +/- 0.07). We also derive an equatorial rotation velocity of 29 +/- 7 km s-1. Moreover, we show that the observed non-equidistance of the l = 1 triplet can be reproduced by the second-order effects of rotation. Finally, we show that the observed rotational splitting of two modes cannot rule out a rigid rotation model.

Dates et versions

hal-03732710 , version 1 (21-07-2022)

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Citer

Maryline Briquet, Thierry Morel, Anne Thoul, Richard Scuflaire, Andrea Miglio, et al.. An asteroseismic study of the beta Cephei star theta Ophiuchi: constraints on global stellar parameters and core overshooting. Monthly Notices of the Royal Astronomical Society, 2007, 381, pp.1482-1488. ⟨10.1111/j.1365-2966.2007.12142.x⟩. ⟨hal-03732710⟩
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