Presentation 1 : Oral
Mapping abundance inhomogeneities and magnetic fields of CP stars with optical aperture synthesis arrays (PNPS)
K. ROUSSELET-PERRAUT, C. STEHLE, T. LANZ, G. MATHYS et al.
Simultaneously mapping abundance inhomogeneities and magnetic fields of
chemical particular (CP) stars is of strong interest to better understand
the key role of magnetism in the atmosphere structuration, in ion migration
and chemical stratification in particular. But since magnetic fields and
chemical inhomogeneities are closely related, they link to similar effects
on classical observables and we are more often obliged to reconstruct
magnetic and abundance maps either independantly or according to several
assumptions. To overcome that, we propose to take benefit of optical
aperture synthesis arrays to resolve local magnetic structures and patchy
stellar surfaces. This requires to be able to polarimetrically resolve
magnetic 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 thanks to visibility and phase
measurements in circularly polarized light and to map abundance
inhomogeneities thanks to "classical" interferometric measurements
(i.e. without the polarimeter). In this poster we show how 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 illustrate that on various typical cases of magnetic
topology and abundance distribution and we detail the case of the
well-known CP star alpha2CVn on which we provide the expected results
with the operation instruments.