VSOP: the variable star one-shot project ^*

I. Project presentation and first data release

¹ Gemini Observatory, 670 N. A'ohoku Pl., Hilo, HI 96720, USA e-mail: tdall@gemini.edu
² Laboratoire d'AstrOphysique de Grenoble, 414 rue de la Piscine, 38400 Saint-Martin d'Hères, France
³ European Southern Observatory, Karl Schwarzschild-Str. 2, 85748 Garching bei München, Germany
⁴ European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Vitacura, Santiago, Chile
⁵ McDonald Observatory and Department of Astronomy, The University of Texas, Austin, TX 78712-1083, USA
⁶ School of Physics A28, University of Sydney, 2006 NSW, Australia
⁷ Universidad de Granada-IAA(CSIC), PO Box 3004, 18080 Granada, Spain
⁸ Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C, Denmark
⁹ Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, 9000 Gent, Belgium
¹⁰ Pontificia Universidad Catolica de Chile, Vicuna Mackenna 4860, Santiago de Chile, Chile
¹¹ Instituto de Astrofísica de Andalucía, Camino Bajo de Huétor 50, 18008 Granada, Spain
¹² Department of Artificial Intelligence, ETSI Informática, Juan del Rosal 16, 28040 Madrid, Spain
¹³ Astrophysikalisches Institut und Universitäts-Sternwarte Jena, Schillergässchen 2, 07745 Jena, Germany

Received: 29 March 2007
Accepted: 28 May 2007

Abstract

Context.About 500 new variable stars enter the General Catalogue of Variable Stars (GCVS) every year. Most of them however lack spectroscopic observations, which remains critical for a correct assignement of the variability type and for the understanding of the object.

Aims.The Variable Star One-shot Project (VSOP) is aimed at (1) providing the variability type and spectral type of all unstudied variable stars, (2) process, publish, and make the data available as automatically as possible, and (3) generate serendipitous discoveries. This first paper describes the project itself, the acquisition of the data, the dataflow, the spectroscopic analysis and the on-line availability of the fully calibrated and reduced data. We also present the results on the 221 stars observed during the first semester of the project.

Methods.We used the high-resolution echelle spectrographs HARPS and FEROS in the ESO La Silla Observatory (Chile) to survey known variable stars. Once reduced by the dedicated pipelines, the radial velocities are determined from cross correlation with synthetic template spectra, and the spectral types are determined by an automatic minimum distance matching to synthetic spectra, with traditional manual spectral typing cross-checks. The variability types are determined by manually evaluating the available light curves and the spectroscopy. In the future, a new automatic classifier, currently being developed by members of the VSOP team, based on these spectroscopic data and on the photometric classifier developed for the COROT and Gaia space missions, will be used.

Results.We confirm or revise spectral types of 221 variable stars from the GCVS. We identify 26 previously unknown multiple systems, among them several visual binaries with spectroscopic binary individual components. We present new individual results for the multiple systems V349 Vel and BC Gru, for the composite spectrum star V4385 Sgr, for the T Tauri star V1045 Sco, and for DM Boo which we re-classify as a BY Draconis variable. The complete data release can be accessed via the VSOP web site.