The plague of magnetic spots among the hot stars of globular clusters: a bridge between MS and WD stars

Bibcode
2021osvm.confE..13M
DOI
10.5281/zenodo.5011601
Momany, Y.; Zaggia, S.; Montalto, M.; Jones, D.; Boffin, H. M. J.; Cassisi, S.; Moni Bidin, C.; Gullieuszik, M.; Saviane, I.; Monaco, L.; Mason, E.; Girardi, L.; Dorazi, V.; Piotto, G.; Milone, A. P.; Lala, H.; Stetson, P. B.; Beletsky, Y.
Bibliographical reference

OBA Stars: Variability and Magnetic Fields. On-line conference

Advertised on:
4
2021
Number of authors
18
IAC number of authors
1
Citations
0
Refereed citations
0
Description
I will report on our recent discovery of a wide-spread photometric variability among hot (~20,000 – 30,000 K) extreme horizontal branch (EHB) stars in Galactic globular clusters. The EHB variability is periodic, displaying single-wave, low-amplitude and ~2-50 days modulations. The variability cannot be ascribed to either binary evolution or pulsation and it is attributed to the presence of magnetic spots: superficial chemical inhomogeneities whose projected rotation induces the variability. We conclude that weak magnetism (<= 400 G) is a key player driving the formation and evolution of EHB clusters stars and, likewise, operating in the Galactic field sdB counterparts. Furthermore, our results suggest similar variability/magnetism phenomena in all radiative-enveloped (MS/WD) hot-stars, in the same temperature regime.
Type
Non-refereed

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