Multiple, short-lived "stellar prominences" on the O giant xi Persei: a magnetic star?

N. Sudnik(1) and H.F. Henrichs(2)

(1) Belarussian State Pedagogical University, 220050, Sovetskaya 18, Minsk, Belarus
(2) Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands

We present strong evidence for a rotation period of 2.0406 d of the O giant xi Persei, derived from the N IV 1718 wind line in 12 yr of IUE data. We predict that xi Per has a magnetic dipole field, with superposed variable magnetic prominences. Favorable dates for future magnetic measurements can be predicted. We also analysed time-resolved He II 4686 spectra from a campaign in 1989 by using the same simplified model as before for lambda Cephei, in terms of multiple spherical blobs attached to the surface, called stellar prominences (Sudnik & Henrichs 2016). These represent transient multiple magnetic loops on the surface, for which we find lifetimes of mostly less than 5 h.

Reference: Contrib. Astron. Obs. Skalnat´e Pleso 48, 1 – 2, (2018)
Status: Conference proceedings


Comments: Proceedings "Stars with a stable magnetic field: from pre-main sequence to compact remnants", Brno, Czech Republic, August 28 - September 01, 2017