Castro, N.; Fossati, L.; Hubrig, S.; Järvinen, S. P.; Przybilla, N.; Nieva, M.-F.; Ilyin, I.; Carroll, T. A.; Schöller, M.; Langer, N.; Schneider, F. R. N.; Simón-Díaz, S.; Morel, T.; Butler, K.; BOB Collaboration
Bibliographical reference
Astronomy and Astrophysics, Volume 597, id.L6, 6 pp.
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1
2017
Journal
Citations
25
Refereed citations
21
Description
The origin and evolution of magnetism in OB stars is far from being well
understood. With approximately 70 magnetic OB stars known, any new
object with unusual characteristics may turn out to be a key piece of
the puzzle. We report the detection of an exceptionally strong magnetic
field in the He-strong B2IV star CPD -62° 2124. Spectropolarimetric
FORS2 and HARPSpol observations were analysed by two independent teams
and procedures, concluding on a strong longitudinal magnetic field of
approximately 5.2 kG. The quantitative characterisation of the stellar
atmosphere yields an effective temperature of 23 650 ± 250 K, a
surface gravity of 3.95 ± 0.10 dex and a surface helium fraction
of 0.35 ± 0.02 by number. The metal composition is in agreement
with the cosmic abundance standard, except for Mg, Si and S, which are
slightly non-solar. The strong and broad ( 300 km s-1)
disc-like emission displayed by the Hα line suggests a centrifugal
magnetosphere supported by the strong magnetic field. Our results imply
that CPD -62° 2124 is an early B-type star hosting one of the
strongest magnetic fields discovered to date, and one of the most
evolved He-strong stars known, with a fractional main-sequence lifetime
of approximately 0.6.
Based on observations made with ESO telescopes at the La Silla and
Paranal observatories under programme ID 191.D-0255(G,I).
Related projects
The IACOB project: A new Era in the Study of Galactic OB Stars
IACOB is an ambitious long-term project whose main scientific goal is to provide an unprecedented empirical overview of the main physical properties of Galactic massive O- and B-type stars which can be used as definitive anchor point for our theories of stellar atmospheres, winds, interiors and evolution of massive stars
Sergio
Simón Díaz