A plague of magnetic spots among the hot stars of globular clusters

Momany, Y.; Zaggia, S.; Montalto, M.; Jones, D.; Boffin, H. M. J.; Cassisi, S.; Bidin, C. Moni; Gullieuszik, M.; Saviane, I; Monaco, L.; Mason, E.; Girardi, L.; D'Orazi, V; Piotto, G.; Milone, A. P.; Lala, H.; Stetson, P. B.; Beletsky, Y.
2020
NATURE ASTRONOMY
DOI
10.1038/s41550-020-1113-4
Two sources of variability are reported in extreme horizontal branch (EHB) stars found in globular clusters, both related to the action of weak magnetic fields: large surface spots and very energetic flares. EHB stars in clusters can thus be linked to EHB field stars, and beyond, to other stars with radiative envelopes.