2007MNRAS.381.1482B

We present a seismic study of the β Cephei star θ 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 p₁and 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 ±0.3M_☉) and central hydrogen abundance (X_c= 0.38±0.02) of θ Oph and to prove the occurrence of core overshooting (α_ov = 0.44±0.07). We also derive an equatorial rotation velocity of 29±7 km/s. 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.