High-frequencies in TESS A–F main sequence stars

Abstract

The driving mechanism for high-frequency oscillations in some chemically peculiar Ap stars, the roAp stars, is not understood. The TESS data provide an ideal opportunity to extend the number of roAp stars which might provide further clues to address this problem. From an examination of over 18000 stars in TESS sectors 1–7, we have discovered high-frequency pulsations in 14 A–F stars, of which only 3 are classified as Ap stars. In addition to these new discoveries, we discuss the frequencies in 9 previously known roAp stars. In one of these stars, HD 60435, we confirm a previous finding that the pulsations have lifetimes of only a few days. In another known roAp star, HD 6532, the relative amplitudes of the rotationally-modulated sidelobes, which are generally used to estimate the inclination of the magnetic axis relative to the rotational axis, are significantly different from those found in ground-based B-band photometric observations. We also discuss 4 δ Scuti stars which appear to have independent frequencies similar to those of roAp stars.