Towards a seismic model of the d Scuti star XX Pyxidis

Author(s): Aleksiej Pamiatnych, Wojciech A. Dziembowski, Gerald Handler, Holger Pikall
Abstract: Frequencies of 13 oscillation modes in the star XX Pyxidis (CD-24 7599) are accurately measured but for none of the modes the spherical harmonic degree (l) is known. We present results of an attempt to construct the model whose low-l mode frequencies reproduce possibly close the observations. Models are constrained by the mean photometric and spectroscopic data for the star. However, the strongest constraint on the effective temperture is from the requirement that the modes excited in the star fall into the range of the modes driven by the opacity mechanism. Our models are built with the standard stellar evolution code allowing no overshooting from the convective core. Effects of rotation are taken into account both in stellar evolution and in linear nonadiabatic oscillation calculations. Uniform rotation rate and conservation of the global angular momentum during evolution are assumed. We find several distinct mode identifications and associated stellar models leading to frequency fits of similar quality. Determination of the l values for some of the modes could remove the ambiguity. None of the fits is satifactory: the mean departures exceed the mean observational frequency error by at least one order of magnitude. The fits could be improved by means of adjusting model parameters that were kept fixed. However, such effort will be meaningful only after improving accuracy in calculation of the effects of rotation in oscillation frequencies.
Organisation(s): Department of Astrophysics
External organisation(s): Polish Academy of Sciences (PAS), Russian Academy of Sciences
Journal: Astronomy & Astrophysics
Volume: 333
Pages: 141-150
No. of pages: 10
ISSN: 0004-6361
Publication date: 1998
Peer reviewed: Yes
Austrian Fields of Science 2012: 103003 Astronomy
Portal url: https://ucrisportal.univie.ac.at/en/publications/6037dfba-708d-4f03-a420-7a22d3615b68

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