Stellar differential rotation and inclination angle from spectro-interferometry

¹ Laboratoire Universitaire d'Astrophysique de Nice (LUAN) - UMR 6525, Univ. de Nice-Sophia Antipolis, Parc Valrose, 06108 Nice Cedex 02, France
² Observatoire de la Côte d'Azur (OCA), Dépt. Fresnel, UMR 6528, Av. Nicolas Copernic, 06130 Grasse, France
³ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
⁴ Institut d'Astrophysique de Paris (IAP), 98bis, Bd Arago, 75014 Paris, France
⁵ Astronomical Observatory Belgrade, MNTRS 1940, Volgina 7, 11050 Beograd, Yugoslavia
⁶ Instituto de Astronomia, Geofísica e Ciências Atmosféricas da Universidade de São Paulo (IAG-USP), CP 9638, 01065-970 São Paulo (SP), Brazil

Corresponding author: A. Domiciano de Souza, Armando.Domiciano@obs-azur.fr

Received: 5 May 2003
Accepted: 15 January 2004

Abstract

Differential interferometry (DI) is a technique that combines high spectral resolution with high spatial resolution. It is particularly suited to probe mechanisms that induce chromatic signatures, such as large scale mass motions. We thus investigate the use of DI combined with the Fourier transform method to study the stellar surface differential rotation. We show that, compared to spectroscopy, DI has the double advantage of allowing the use of all available Fourier frequencies as well as of disentangling the stellar differential rotation rate and the inclination angle. We derive some reference analytical expressions of DI observables. It is shown that the foreseen instrumental performances of the spectro-interferometer VLTI/AMBER are high enough to study the stellar differential rotation.