Issue |
A&A
Volume 450, Number 3, May II 2006
|
|
---|---|---|
Page(s) | 1157 - 1171 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361:20054326 | |
Published online | 19 April 2006 |
Recovery of the global magnetic field configuration of 78 Virginis from Stokes IQUV line profiles
1
Département de Physique et d'Astronomie, Université de Moncton, Moncton, N.-B., E1A 3E9, Canada e-mail: khalakv@umoncton.ca
2
Main Astronomical Observatory, 27 Zabolotnoho Str., 03680 Kyiv, Ukraine
3
Department of Physics, Royal Military College of Canada, PO Box 17000 stn “FORCES”, Kingston, Ontario, K7K 4B4 Canada
Received:
9
October
2005
Accepted:
25
January
2006
The surface magnetic field configuration of the Ap star
HD 118022 (78 Vir) has been reconstructed in the framework of the
magnetic charge distribution (MCD) method from the analysis of
Stokes spectra obtained using the MuSiCoS spectropolarimeter at Pic du Midi Observatory.
Magnetically-sensitive Fe ii lines were primarily employed
in the analysis, supposing that iron is evenly distributed over
the stellar surface. We show that the Stokes
profile shapes
and variations of 78 Vir can be approximately fit assuming a global magnetic field configuration described by a slightly decentered, inclined magnetic dipole of polar surface intensity
approximately 3.3 kG. The derived inclinations of the stellar
rotational axis to the line of sight
±
as well as
to the magnetic dipole axis
±
are in good
agreement with previous estimations by other authors, whereas the
sky-projected position angle of the stellar rotation axis
is reported here for the first time.
In addition, several lines of Cr ii and Ti ii were
studied, yielding evidence for non-uniform surface distributions
of these elements, and magnetic field results similar to those
derived from Fe.
Key words: stars: chemically peculiar / stars: magnetic fields / polarization / stars: individual: 78 Virginis (HD 118022)
© ESO, 2006
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