AUTHOR=Balona Luis A. 

TITLE=Spots and Flares in Hot Main Sequence Stars Observed by Kepler, K2, and TESS

JOURNAL=Frontiers in Astronomy and Space Sciences

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/astronomy-and-space-sciences/articles/10.3389/fspas.2021.580907

DOI=10.3389/fspas.2021.580907

ISSN=2296-987X

ABSTRACT=<p>About 22,000 <italic>Kepler</italic> stars, 7,000 <italic>K2</italic> stars, and nearly 60,000 <italic>TESS</italic> stars from sectors 1–24 have been classified according to variability type. A large proportion of stars of all spectral types appear to have periods in their light curves consistent with the expected rotation periods. A previous analysis of A- and late B-type stars suggests that these stars are indeed rotational variables. In this paper we have accumulated data to show that rotational modulation is present in about 30–40% of A- and B-type stars. A search for flares in <italic>TESS</italic> A- and B-type stars resulted in the detection of 102 flares in 57 stars. Analysis of flare energies show that the source of the flares cannot be a cool dwarf companion nor a F/G giant. The realization that a considerable fraction of A- and B-type stars are active indicates that a revision of current concepts regarding hot star envelopes is required.</p>