Nonradial p-modes in the G9.5 giant [epsilon] Ophiuchi? Pulsation model fits to MOST photometry

Abstract

The G9.5 giant [epsilon] Oph shows evidence of radial p-mode pulsations in both radial velocity and luminosity. We re-examine the observed frequencies in the photometry and radial velocities and find a best model fit to 18 of the 21 most significant photometric frequencies. The observed frequencies are matched to both radial and nonradial modes in the best model fit. The small scatter of the frequencies about the model predicted frequencies indicate that the average lifetimes of the modes could be as long as 10–20 d. The best fit model itself, constrained only by the observed frequencies, lies within [plus or minus] 1 [sigma] of [epsilon] Oph’s position in the HR-diagram and the interferometrically determined radius.