EDP Sciences
Free access
Issue
A&A
Volume 365, Number 2, January II 2001
Page(s) 118 - 127
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20000450


A&A 365, 118-127 (2001)
DOI: 10.1051/0004-6361:20000450

Spectropolarimetric measurements of the mean longitudinal magnetic field of chemically peculiar stars

II. Phase relating the magnetic and luminosity variabilities
F. Leone1 and G. Catanzaro2 .

1  Osservatorio Astrofisico di Catania, Città Universitaria, 95125 Catania, Italy
2  Center for Astrophysical Sciences, The Johns Hopkins University, Dept. of Physics and Astronomy, Bloomberg Center, 3400 N. Charles str., Baltimore, MD 21218, USA

(Received 21 June 2000 / Accepted 19 September 2000)

Abstract
For a sample of chemically peculiar stars, we report time-resolved measurements of the effective magnetic field which were obtained with the spectropolarimetry operating at the Catania Astrophysical Observatory. These observations are combined with data from the literature for better pointing out that periodic magnetic variability which characterises this class of stars. Periods given in the literature have been checked and, if possible, re-determined, not only by means of the magnetic measurements but referring also to the Hipparcos photometry. The variability of the effective magnetic field of the already known magnetic star 25 Sex is pointed out for the first time. As to the suspected magnetic chemically peculiar star EP UMa, our measurements confirm that this is really a magnetic star and we indicate a possible variability period. The accuracy of the variability period for CS Vir and FF Vir is improved. The suggestion that light variability is due to the re-distribution of ultraviolet flux towards the visible wavelengths in metal rich regions, which are not homogeneously distributed on the stellar surface, appears not always and straightly valid. Local line-blocking is certainly important in the case of CS Vir and a direct influence of the magnetic field on the infrared photometric variability cannot be ruled out for 25 Sex.


Key words: stars: chemically peculiar -stars: magnetic fields

Offprint request: F. Leone, fleone@sunct.ct.astro.it

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