A short and sudden increase of the magnetic field strength and the accompanying spectral variability in the O9.7 V star HD 54879
Abstract
Only 11 O-type stars have been confirmed to possess large-scale organized magnetic fields. The presence of a -600 G longitudinal magnetic field in the O9.7 V star HD 54879 with a lower limit of the dipole strength of ∼2 kG was discovered a few years ago in the framework of the ESO large program `B-fields in OB stars'. Our FORS 2 spectropolarimetric observations from 2017 October 4 to 2018 February 21 reveal the presence of short- and long-term spectral variability and a gradual magnetic field decrease from about -300 G down to about -90 G. Different scenarios are discussed in an attempt to interpret our observations. Our FORS 2 radial velocity measurements indicate that HD 54879 is a member of a long-period binary.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- April 2019
- DOI:
- arXiv:
- arXiv:1901.03975
- Bibcode:
- 2019MNRAS.484.4495H
- Keywords:
-
- MHD;
- stars: atmospheres;
- stars: early-type;
- stars: individual: HD 54879;
- stars: magnetic field;
- stars: variables: general;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 13 pages, 4 tables, 14 figures, accepted for publication in MNRAS