Issue |
A&A
Volume 413, Number 3, January III 2004
|
|
---|---|---|
Page(s) | 1087 - 1093 | |
Section | Stellar atmospheres | |
DOI | https://doi.org/10.1051/0004-6361:20031600 | |
Published online | 07 January 2004 |
No evidence of a strong magnetic field in the Blazhko star RR Lyrae*
1
Observatoire de la côte d'Azur, UMR 6528, BP 4229, 06304 Nice Cedex 04, France
2
Department of Physics, Royal Military College of Canada, PO Box 17000, Station “Forces”, Kingston, Ontario, Canada K7K 4B4
3
Department of Physics & Astronomy, the University of Western Ontario, London, Ontario, Canada N6A 3K7
Corresponding author: M. Chadid, chadid@obs-nice.fr
Received:
9
April
2003
Accepted:
9
October
2003
In this paper we report a new series of high-precision (median
G) longitudinal magnetic field measurements of
RR Lyrae, the brightest Blazhko star, obtained with the MuSiCoS
spectropolarimeter over a period of almost 4 years from 1999-2002. These data
provide no evidence whatsoever for a strong magnetic field in the
photosphere of RR Lyrae, a result consistent with Preston's ([CITE])
results, but inconsistent with apparent magnetic field detections by
Babcock ([CITE]) and Romanov et al. ([CITE], [CITE]). Following discussion
of these disparate results, we conclude that RR Lyrae is a bona
fide non-magnetic star, a conclusion which leads to the general
falsification of models of the Blazkho effect requiring strong
photospheric magnetic fields. Furthermore, due to the 4 year baseline of our observations,
we can also dismiss the hypothesis that RR Lyrae undergoes a 4-year “magnetic cycle”.
Therefore the origin of the
observed 4–year modulation of RR Lyrae remains unexplained, and we stress the
need for additional theoretical efforts to come to a better
understanding of this phenomenon.
Key words: stars: variables: RR Lyr / stars: oscillations / stars: magnetic fields / stars: individual: RR Lyrae / techniques: spectroscopic, polarimetric
© ESO, 2004
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