Title: An asteroseismic study of the beta Cephei star theta Ophiuchi: constraints on global stellar parameters and core overshooting
Authors: Briquet, Maryline ×
Morel, Thierry
Thoul, A
Scuflaire, R
Miglio, A
Montalban, J
Dupret, M.-A
Aerts, Conny #
Issue Date: Nov-2007
Publisher: Priestley and Weale
Series Title: Monthly Notices of the Royal Astronomical Society vol:381 issue:4 pages:1482-1488
Abstract: 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 p(1) and the quintuplet as g(1). 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 epsilon [0.71, 0.7211] and Z epsilon [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 +/- 0.3 M circle dot) and central hydrogen abundance (X-c = 0.38 +/- 0.02) of theta Oph and to prove the occurrence of core overshooting (alpha(ov) = 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.
ISSN: 0035-8711
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Institute of Astronomy
× corresponding author
# (joint) last author

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