Short-period pulsating hot-subdwarf stars observed by TESS II. Northern ecliptic hemisphere

TL;DR

This paper reports the discovery and analysis of 50 short-period pulsating hot subdwarf stars observed by TESS in the northern ecliptic hemisphere, including new and hybrid pulsators, with insights into their rotation and evolutionary status.

Contribution

It presents the identification of 50 hot subdwarf pulsators from TESS data, including 26 new discoveries, and analyzes their pulsation properties and rotation periods.

Findings

26 new pulsators discovered by TESS

Identification of hybrid pulsators with both low and high frequencies

Detection of candidate rotation periods between 11 and 46 days

Abstract

We present results of a continuation of our Transiting Exoplanet Survey Satellite (TESS) search for short-period pulsations in compact stellar objects observed during Years 2 and 4 of the TESS mission that targeted the northern ecliptic hemisphere. For many of the targets, we exploit unpublished spectroscopic data to confirm or determine the object's spectral classification. From the TESS photometry, we identify 50 short-period hot-subdwarf pulsators, including 35 sdB and 15 sdOB stars. The sample contains 26 pulsators not known before the TESS mission. Nine stars show signals at both low and high frequencies, and are therefore ``hybrid'' pulsators. For each pulsator, we report the list of prewhitened frequencies and we show amplitude spectra calculated from the TESS data. We attempt to identify possible multiplets caused by stellar rotation, and we report five candidates with rotation periods between 11 and 46d. Having the search for p-mode pulsating hot subdwarfs in TESS Sectors 1 - 60 done, we discuss the completeness of the study, as well as instability strip and the evolutionary status of the stars we found. We also compare the distribution of pulsation periods as a function of effective temperature and surface gravity with theoretical predictions.