ASTEROSEISMOLOGY OF HYBRID PULSATORS MADE POSSIBLE: SIMULTANEOUS <i>MOST</i> SPACE PHOTOMETRY AND GROUND-BASED SPECTROSCOPY OF γ PEG

Abstract

We have acquired simultaneous high-precision space photometry and radial\nvelocities of the bright hybrid Beta Cep/SPB pulsator Gamma Peg. Frequency\nanalyses reveal the presence of six g modes of high radial order together with\neight low-order Beta Cep oscillations in both data sets. Mode identification\nshows that all pulsations have spherical degrees l = 0 - 2. An 8.5 solar mass\nmodel reproduces the observed pulsation frequencies; all theoretically\npredicted modes are detected. We suggest, contrary to previous authors, that\nGamma Peg is a single star; the claimed orbital variations are due to g-mode\npulsation. Gamma Peg is the first hybrid pulsator for which a sufficiently\nlarge number of high-order g modes and low order p and mixed modes have been\ndetected and identified to be usable for in-depth seismic modeling.\n