Astron. Astrophys. Suppl. Ser. 134, 149-159

A dedicated polarimeter for the MuSiCoS échelle spectrograph

J.-F. Donati¹ - C. Catala¹ - G.A. Wade² - G. Gallou¹ - G. Delaigue¹ - P. Rabou³

Send offprint request: J.-F. Donati

1 - Laboratoire d'Astrophysique, Observatoire Midi-Pyrénées, F-31400 Toulouse, France
2 - Department of Physics and Astronomy, The University of Western Ontario, London Ontario, Canada N6A 3K7
3 - Laboratoire d'Astrophysique, Observatoire de Grenoble, 414 rue de la Piscine, BP. 53, F-38041 Grenoble Cedex 9, France

Received May 18; accepted July 16, 1998

Abstract:

We present in this paper the technical characteristics of a new polarimetric unit dedicated to the MuSiCoS échelle spectrograph. The first test runs indicate that our instrument is very good at measuring polarisation or depolarisation structures in line profiles. It is therefore one of the very few facilities worldwide for studying magnetic topologies of active and chemically peculiar stars through rotational modulation of linearly and circularly polarised Zeeman signatures in line profiles. It is also a very interesting tool for investigating geometries of non-axisymmetric circumstellar environments through depolarisation of spectral lines formed within the scattering envelope.

Key words: stars: magnetic fields -- stars: circumstellar matter -- line: profiles -- polarization -- instrumentation: polarimeters