A search for variable subdwarf B stars in TESS Full Frame Images II. Variable objects in the northern ecliptic hemisphere

TL;DR

This study searches for pulsating subdwarf B stars in TESS Full Frame Images of the northern ecliptic hemisphere, identifying new candidates, variable objects, and eclipsing binaries, expanding the catalog of variable hot subdwarfs.

Contribution

It reports the discovery of new pulsating subdwarf B stars, candidates, and variable objects in TESS data, providing detailed mode analysis and orbital parameters for selected systems.

Findings

13 likely new pulsating subdwarf B stars

506 variable objects identified

33 eclipsing binary systems analyzed

Abstract

We report the results of our search for pulsating subdwarf B stars in Full Frame Images collected during Year 2 of the TESS mission and covering the northern ecliptic hemisphere. This is a continuation of our effort we presented in Paper I. We found 13 likely new pulsating subdwarf B stars, 10 pulsating candidates that are identified as other hot subdwarfs, and 30 spectroscopically unclassified objects that show amplitude spectra typical of pulsating subdwarf B stars. We found 506 variable objects, most of them spectroscopically unclassified, hence their specific variability class yet to be confirmed. Eclipsing binaries with sharp eclipses sample comprises 33 systems. For 12 of them we derived precise orbital periods and checked their stabilities. We identified one known and five new candidate HW Vir systems. The amplitude spectra of the 13 likely sdB pulsators are not rich in modes, hence any further analysis is not possible. However, we selected three candidates for pulsating subdwarf B stars that show the richest amplitude spectra and we performed a mode identification deriving modal degrees of most of the detected modes. In total, in both ecliptic hemispheres, we found 15 likely pulsating pulsating subdwarf B stars, additional 10 candidates for pulsating subdwarf B stars, 66 other variable subdwarf B stars, 2076 spectroscopically unconfirmed variable stars, and 123 variable non-sdB stars.