Exploring the internal rotation of GW Vir stars through asteroseismology

A. H. CÓRSICO; L. G. ALTHAUS

Tubingen

Workshop; 17TH EUROPEAN WHITE DWARF WORKSHOP; 2010

Stellar rotation breaks the spherical symmetry of a star, and in the case of a pulsating star, it removes the intrinsic mode degeneracy of a nonradial g-mode characterized by an harmonic degree and a radial order . As a result, each pulsation frequency is split into multiplets of frequencies specified by different values of the azimuthal index m. Here, we explore the potential of asteroseismology to place constraints on the internal rotation of pulsating PG1159 stars, also known as GW Vir variables. We employ dedicated seismological models for the pulsating PG1159 stars PG 0122+200, PG 1159−035, and RX J2117+3412 in order to accurately assess the expected frequency splittings induced by rotation, and compare them with the observed ones. To this end, we assume different types of very simplified internal rotation profiles. We found that while PG 1159−035 definitely rotates as a rigid body, PG 0122+200 and RX J2117+3412 appear to be spinning with a rotation rate that depends on the depth.