MOST observations of the roAp stars HD 9289, HD 99563, and HD 134214

TL;DR

This study utilizes high-precision space-based photometry from the MOST satellite to analyze pulsations in three roAp stars, revealing new frequencies, rotation periods, and detailed mode structures, advancing understanding of stellar oscillations.

Contribution

The paper provides the first measurement of the rotation period of HD 9289 and identifies numerous new pulsation frequencies in all three stars, offering detailed mode analyses and insights into their pulsation spectra.

Findings

HD 9289's rotation period is 8.5 days.

11 pulsation frequencies detected in HD 134214, 9 of which are new.

HD 134214 exhibits a well-defined large frequency spacing.

Abstract

We report on the analysis of high-precision space-based photometry of the roAp (rapidly oscillating Ap) stars HD 9289, HD 99563, and HD134214. All three stars were observed by the MOST satellite for more than 25 days, allowing unprecedented views of their pulsation. We find previously unknown candidate frequencies in all three stars. We establish the rotation period of HD 9289 (8.5 d) for the first time and show that the star is pulsating in two modes that show different mode geometries. We present a detailed analysis of HD 99563's mode multiplet and find a new candidate frequency which appears independent of the previously known mode. Finally, we report on 11 detected pulsation frequencies in HD 134214, 9 of which were never before detected in photometry, and 3 of which are completely new detections. Thanks to the unprecedentedly small frequency uncertainties, the p-mode spectrum of HD 134214 can be seen to have a well-defined large frequency spacing similar to the well-studied roAp star HD 24712 (HR 1217).