EDP Sciences
Free Access
Volume 392, Number 2, September III 2002
Page(s) 637 - 652
Section Stellar atmospheres
DOI https://doi.org/10.1051/0004-6361:20021192

A&A 392, 637-652 (2002)
DOI: 10.1051/0004-6361:20021192

A highly sensitive search for magnetic fields in B, A and F stars

S. L. S. Shorlin1, G. A. Wade2, J.-F. Donati3, J. D. Landstreet1, 3, P. Petit3, T. A. A. Sigut1 and S. Strasser1, 4

1  Physics & Astronomy Department, The University of Western Ontario, London, Ontario, N6A 3K7 Canada
2  Department of Physics, Royal Military College of Canada, Kingston, Ontario, K7K 7B4 Canada
3  Observatoire Midi-Pyrénées, 14 avenue Édouard Belin, 31400 Toulouse, France
4  Physics and Astronomy Department, University of Calgary, Calgary, Alberta, T2N 1N4 Canada

(Received 27 March 2002 / Accepted 20 June 2002)

Circular spectropolarimetric observations of 74 stars were obtained in an attempt to detect magnetic fields via the longitudinal Zeeman effect in their spectral lines. The sample observed includes 22 normal B, A and F stars, four emission-line B and A stars, 25 Am stars, 10 HgMn stars, two $\lambda$ Boo stars and 11 magnetic Ap stars. Using the Least-Squares Deconvolution multi-line analysis approach (Donati et al. 1997), high precision Stokes I and V mean signatures were extracted from each spectrum. We find absolutely no evidence for magnetic fields in the normal, Am and HgMn stars, with upper limits on longitudinal field measurements usually considerably smaller than any previously obtained for these objects. We conclude that if any magnetic fields exist in the photospheres of these stars, these fields are not ordered as in the magnetic Ap stars, nor do they resemble the fields of active late-type stars. We also detect for the first time a field in the A2pSr star HD 108945 and make new precise measurements of longitudinal fields in five previously known magnetic Ap stars, but do not detect fields in five other stars classified as Ap SrCrEu. We also report new results for several binary systems, including a new $v\sin i$ for the rapidly rotating secondary of the Am- $\delta$ Del SB2 HD 110951.

Key words: line: profiles -- polarization -- stars: chemically peculiar -- stars: magnetic fields -- stars: atmospheres

Offprint request: S. L. S. Shorlin, sshorlin@astro.uwo.ca

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© ESO 2002