Frequency ratio method for seismic modelling of γ Doradus stars

II. The role of rotation

¹ Instituto de Astrofísica de Andalucía (CSIC), CP3004, Granada, Spain e-mail: jcsuarez@iaa.es
² LESIA, Observatoire de Paris-Meudon, UMR 8109, France
³ ESO Office Santiago, Alonso de Cordova 3107, Santiago 19, Chile

Received: 22 March 2005
Accepted: 26 July 2005

Abstract

The effect of rotation on the Frequency Ratio Method (Moya et al. 2005, A&A, 432, 189) is examined. Its applicability to observed frequencies of rotating γ Doradus stars is discussed taking into account the following aspects: the use of a perturbative approach to compute adiabatic oscillation frequencies; the effect of rotation on the observational Brunt–Väisälä integral determination and finally, the problem of disentangling multiplet-like structures from frequency patterns due to the period spacing expected for high-order gravity modes in asymptotic regime. This analysis reveals that the FRM produces reliable results for objects with rotational velocities up to , for which the FRM intrinsic error increases one order of magnitude with respect to the typical FRM errors given in Moya et al. (2005, A&A, 432, 189). Our computations suggest that, given the spherical degree identification, the FRM may be discriminating for modes, in the sense that the method avoids any misinterpretation induced by the presence of rotationally split multiplet-like structures, which reinforces the robustness of the method. However, if is unknown, such discrimination is not ensured. In order to check the FRM in presence of slow-moderate rotation, we have applied it to the three observed frequencies of the slowly rotating () γ Doradus star HD 48501.