Multi-site, multi-technique survey of γ Doradus candidates^*

I. Spectroscopic results for 59 stars

¹ Observatoire de la Côte d'Azur, Dpt. Fresnel, UMR 6528, 06304 Nice Cedex 4, France
² Osservatorio Astronomico di Brera, Via Bianchi 46, 23807 Merate, Italy
³ Instituto de Astrofisica de Andalucia, Apt. 3044, 18080 Granada, Spain
⁴ Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Apdo. Postal 70-264, 04510 Mexico D.F., Mexico
⁵ Observatorio Astronómico Nacional, IA-UNAM, Apto. Postal 877, Ensenada, 22800 B.C., Mexico
⁶ Princeton University Observatory, Princeton, NJ 08544, USA
⁷ Katholieke Universiteit Leuven, Departement Natuurkunde en Sterrenkunde, Celestijnenlaan 200 B, 3001 Leuven, Belgium
⁸ Institute for Astronomy, University of Vienna, Tuerkenschanzstrasse 17, 1180 Vienna, Austria
⁹ National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, PR China

Corresponding author: P. Mathias, mathias@obs-nice.fr

Received: 13 October 2003
Accepted: 25 November 2003

Abstract

We present the first results of a 2-year high-resolution spectroscopy campaign of 59 candidate γ Doradus stars which were mainly discovered from the HIPPARCOS astrometric mission. More than 60% of the stars present line profile variations which can be interpreted as due to pulsation related to γ Doradus stars. For all stars we also derived the projected rotation velocity (up to more than 200 km s^-1). The amplitude ratios for the main HIPPARCOS frequency are in the range 35-96 km s^-1 mag^-1. About 50% of the candidates are possible members of binary systems, with 20 stars being confirmed γ Doradus. At least 6 stars present composite spectra, and in all but one case (for which only one spectrum could be obtained), the narrow component shows line profile variations, pointing towards an uncomfortable situation if this narrow component originates from a shell surrounding the star. This paper is the first of a series concerning mode identification using both photometric and spectroscopic methods for the confirmed γ Doradus stars of the present sample.