Oscillation mode identifications and models for the delta Scuti star FG Virginis
Abstract
We present new spectroscopic and photometric time series observations of the delta Scuti star FG~Vir. We detect the oscillations via changes in the equivalent widths of hydrogen and metal absorption lines. From the ratios between spectroscopic and photometric amplitudes, we assign l values to the eight strongest oscillation modes. In particular, we identify two radial modes (l =0) and find that the main pulsation mode (147 microHz) has l = 1. One of the radial modes (at 140 microHz) is the fundamental, implying that two modes with lower frequencies are g-modes. For the radial modes, we compare frequencies with those calculated from a scaled delta Scuti star model and derive a density 0.1645 +/- 0.0005 rho_sol. We then obtain a distance of 84 +/- 3 pc, in excellent agreement with the Hipparcos value. Finally, we suggest that a 3.5-day variability in all observables (equivalent widths and intensity) is caused by stellar rotation.
Cite
@article{arxiv.astro-ph/9804218,
title = {Oscillation mode identifications and models for the delta Scuti star FG Virginis},
author = {M. Viskum and H. Kjeldsen and T. R. Bedding and T. H. Dall and I. K. Baldry and H. Bruntt and S. Frandsen},
journal= {arXiv preprint arXiv:astro-ph/9804218},
year = {2007}
}
Comments
12 pages, latex with figures. Accepted by A&A