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

TL;DR

This study identifies and models nonradial p-mode pulsations in the G9.5 giant epsilon Oph using MOST photometry, matching observed frequencies to theoretical models and suggesting mode lifetimes of 10-20 days.

Contribution

It provides the first detailed pulsation model fit to epsilon Oph's observed frequencies, including both radial and nonradial modes, constrained by multiple observational data.

Findings

Best model fits 18 of 21 significant frequencies

Observed frequencies match both radial and nonradial modes

Mode lifetimes could be as long as 10-20 days

Abstract

The G9.5 giant eps 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 10-20d. The best fit model itself, constrained only by the observed frequencies, lies within 1 sigma of eps Oph's position in the HR-diagram and the interferometrically determined radius.