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Proceedings Paper

Mapping abundance inhomogeneities and magnetic fields of chemically peculiar (CP) stars with optical aperture synthesis arrays
Author(s): Karine Rousselet-Perraut; Chantal Stehle; Thierry Lanz; Thomas Boudoyen; Slobodan Jankov; Farrokh Vakili; Martin Kilbinger; Jean-Baptiste Lebouquin; Oleg Kochukhov
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Paper Abstract

Simultaneously mapping the abundance inhomogeneities and the magnetic fields of chemically peculiar (CP) stars is essential to improve our understanding of stellar magnetism and its key role in structuring stellar atmospheres, in particular relative to ion migration and chemical stratification. However, magnetic fields and chemical inhomogenities tend to have similar effects on classical observables. Magnetic and abundance maps have therefore to be reconstructed most often either independently or in making a priori assumptions. To overcome these difficulties, we propose to take benefit of optical aperture synthesis arrays to resolve local magnetic structures and patchy stellar surfaces. This requires ability to resolve polarimetrically magnetically-sensitive spectral lines, and thus to add a polarimetric device at the combined focus of an interferometric array. Within this instrumental context, it becomes possible to map magnetic fields with visibility and phase measurements in circularly polarized light and to map the chemical inhomogeneities thanks to "classical" interferometric measurements (i.e. without the polarimeter). In this paper, we show that the interference fringe phase is the suitable observable for polarimetric measurements and for mapping patchy surfaces (see also Jankov et al. in these proceedings). We present some illustrative cases of different magnetic topologies and abundance distributions. We focus on two well-known CP stars, βCrB and α2CVn, and we show observational predictions with different instruments currently in operation (GI2T, VLTI).

Paper Details

Date Published: 21 February 2003
PDF: 7 pages
Proc. SPIE 4838, Interferometry for Optical Astronomy II, (21 February 2003); doi: 10.1117/12.458590
Show Author Affiliations
Karine Rousselet-Perraut, Lab. d'Astrophysique de l'Observatoire de Grenoble (France)
Chantal Stehle, Observatoire de Paris-Meudon (France)
Thierry Lanz, NASA Goddard Space Flight Ctr. (United States)
Observatoire de Paris-Meudon (France)
Thomas Boudoyen, Observatoire de Paris-Meudon (United States)
Observatoire de Paris-Meudon (France)
Slobodan Jankov, Observatoire de la Cote d'Azure (France)
Farrokh Vakili, Univ. de Nice-Sophia Antipolis (France)
Martin Kilbinger, Institut fur Astrophysik und Extraterrestrik/Univ. Bonn (Germany)
Jean-Baptiste Lebouquin, Lab. d'Astrophysique de l'Observatoire de Grenoble (France)
Observatoire de Paris-Meudon (France)
Oleg Kochukhov, Uppsala Astronomical Observatory (Sweden)

Published in SPIE Proceedings Vol. 4838:
Interferometry for Optical Astronomy II
Wesley A. Traub, Editor(s)

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