TESS Cycle 1 observations of roAp stars with 2-min cadence data

Smalley

doi:10.1093/mnras/stab1578

TESS Cycle 1 observations of roAp stars with 2-min cadence data

Smalley

Authors

Barry Smalley b.smalley@keele.ac.uk

Abstract

We present the results of a systematic search for new rapidly oscillating Ap (roAp) stars using the 2-min cadence data collected by the Transiting Exoplanet Survey Satellite (TESS) during its Cycle 1 observations. We identify 12 new roAp stars. Amongst these stars we discover the roAp star with the longest pulsation period, another with the shortest rotation period, and six with multiperiodic variability. In addition to these new roAp stars, we present an analysis of 44 known roAp stars observed by TESS during Cycle 1, providing the first high-precision and homogeneous sample of a significant fraction of the known roAp stars. The TESS observations have shown that almost 60 per cent (33) of our sample of stars are multiperiodic, providing excellent cases to test models of roAp pulsations, and from which the most rewarding asteroseismic results can be gleaned. We report four cases of the occurrence of rotationally split frequency multiplets that imply different mode geometries for the same degree modes in the same star. This provides a conundrum in applying the oblique pulsator model to the roAp stars. Finally, we report the discovery of non-linear mode interactions in $\alpha$ Cir (TIC 402546736, HD 128898) around the harmonic of the principal mode -- this is only the second case of such a phenomenon.

Journal Article Type	Article
Acceptance Date	May 27, 2021
Publication Date	Sep 1, 2021
Journal	Monthly Notices of the Royal Astronomical Society
Print ISSN	0035-8711
Publisher	Oxford University Press
Peer Reviewed	Peer Reviewed
Volume	506
Issue	1
Pages	1073-1110
DOI	https://doi.org/10.1093/mnras/stab1578
Keywords	Solar and Stellar Astrophysics
Publisher URL	https://academic.oup.com/mnras/article/506/1/1073/6289936