Bibcode
Castro, N.; Fossati, L.; Hubrig, S.; Simón-Díaz, S.; Schöller, M.; Ilyin, I.; Carrol, T. A.; Langer, N.; Morel, T.; Schneider, F. R. N.; Przybilla, N.; Herrero, A.; de Koter, A.; Oskinova, L. M.; Reisenegger, A.; Sana, H.; BOB Collaboration
Referencia bibliográfica
Astronomy and Astrophysics, Volume 581, id.A81, 14 pp.
Fecha de publicación:
9
2015
Revista
Número de citas
39
Número de citas referidas
33
Descripción
The number of magnetic stars detected among massive stars is small;
nevertheless, the role played by the magnetic field in stellar evolution
cannot be disregarded. Links between line profile variability,
enhancements/depletions of surface chemical abundances, and magnetic
fields have been identified for low-mass B-stars, but for the O-type
domain this is almost unexplored. Based on FORS 2 and HARPS
spectropolarimetric data, we present the first detection of a magnetic
field in HD 54879, a single slowly rotating O9.7 V star. Using two
independent and different techniques we obtained the firm detection of a
surface average longitudinal magnetic field with a maximum amplitude of
about 600 G, in modulus. A quantitative spectroscopic analysis of the
star with the stellar atmosphere code fastwind results in an effective
temperature and a surface gravity of 33 000 ± 1000 K and 4.0
± 0.1 dex. The abundances of carbon, nitrogen, oxygen, silicon,
and magnesium are found to be slightly lower than solar, but compatible
within the errors. We investigate line-profile variability in HD 54879
by complementing our spectra with spectroscopic data from other recent
OB-star surveys. The photospheric lines remain constant in shape between
2009 and 2014, although Hα shows a variable emission. The Hα
emission is too strong for a standard O9.7 V and is probably linked to
the magnetic field and the presence of circumstellar material. Its
normal chemical composition and the absence of photospheric line profile
variations make HD 54879 the most strongly magnetic, non-variable single
O-star detected to date.
Based on observations made with ESO telescopes at the La Silla and
Paranal observatories under programme ID 191.D-0255(C, F).Appendix A is
available in electronic form at http://www.aanda.org
Proyectos relacionados
Proyecto IACOB: Una Nueva Era en el Estudio de Estrellas OB Galácticas
Massive stars has been many times claimed as Cosmic Engines and Gifts of Nature for the study of the Universe, from the Solar neighbourhood to the large-z Universe. The complete understanding of the physical properties and evolution of massive stars (and their interplay with the ISM) is crucial for many fields of Astrophysics and, ultimately, to
Sergio
Simón Díaz