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Paper: Progress in the Detection of the p-Mode Spectra of roAp Stars: Gamma Equulei and Alpha Circini
Volume: 479, Progress in Physics of the Sun and Stars
Page: 115
Authors: Mkrtichian, D. E.; Hatzes, A. P.
Abstract: We present recent results on α Cir and γ Equ that are part of our program to detect the p-mode oscillation spectrum in roAp stars. In γ Equ, based on precise radial velocity measurements taken with the 2.7-m telescope at the McDonald Observatory, we have discovered four new oscillation modes. The frequencies of these new modes, along with previously known modes, exhibit a well defined large spacing of 62.8 μHz. We conclude that consecutive overtones of even and odd modes are excited in γ Equ. For α Cir we have used a time series of precise radial velocity measurements made with the HARPS (High Accuracy Radial velocity Planet Searcher) spectrograph of ESO's (European Southern Observatory's) 3.6-m telescope at the La Silla Observatory. These reveal a rich, low-amplitude p-mode spectrum of at least thirty-six modes that lie in the interval 2173 – 2641 μHz. The mode amplitudes range from 52 m s-1 to 56 cm s-1. The number and spacing of the modes indicate that we have detected, for the first time, the excited high-degree (ℓ > 3) modes in a roAp star. These discoveries have established new detection limits for asteroseismology of roAp stars.
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