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The spots on Ap stars

Published online by Cambridge University Press:  26 August 2011

Oleg Kochukhov
Oleg Kochukhov*
Affiliation:
Department Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala, Sweden email: oleg.kochukhov@fysast.uu.se
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Abstract

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The upper main sequence magnetic chemically peculiar (Ap) stars exhibit a non-uniform distribution of chemical elements across their surfaces and with height in their atmospheres. These inhomogeneities, responsible for the conspicuous photometric and spectroscopic variation of Ap stars, are believed to be produced by atomic diffusion operating in the stellar atmospheres stabilized by multi-kG magnetic fields. Here I present an overview of the current state-of-the-art in understanding Ap-star spots and their relation to magnetic fields. In particular, I highlight recent 3-D chemical spot structure studies and summarize magnetic field mapping results based on the inversion of the full Stokes vector spectropolarimetric observations. I also discuss a puzzling new type of spotted stars, HgMn stars, in which the formation and evolution of heavy element spots is driven by a poorly understood mechanism, apparently unrelated to magnetic fields.

Keywords

Polarizationstars: chemically peculiarstars: magnetic fieldsstars: atmospheres
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 6 , Symposium S273: The Physics of Sun and Star Spots , August 2010 , pp. 249 - 255
Copyright
Copyright © International Astronomical Union 2011

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