A short and sudden increase of the magnetic field strength and the accompanying spectral variability in the O9.7 V star HD 54879. Issue 4 (18th January 2019)

• Record Type: Journal Article
• Authors: Hubrig, S; Küker, M; Järvinen, S P; Kholtygin, A F; Schöller, M; Ryspaeva, E B; Sokoloff, D D
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 484:Issue 4(2019)
• Page Start: 4495
• Page End: 4506
• Publication Date: 2019-01-18
• Subjects: MHD -- stars: atmospheres -- stars: early-type -- stars: individual: HD 54879 -- stars: magnetic field -- stars: variables: general; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz198
• Languages: English
• ISSNs: 0035-8711

Abstract

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.