A search for very active stars in the Galaxy

First results

¹ Australia Telescope National Facility, CSIRO, PO Box 76, Epping, NSW 1710, Australia e-mail: gregory.tsarevsky@atnf.csiro.au
² Astro Space Center, Lebedev Physical Institute, 84/32 Profsoyuznaya St., 117997 Moscow, Russia
³ Isaac Newton Institute of Chile, Moscow Branch, 13 Universitetskij Pr., Moscow 119992, Russia
⁴ Observatoire de la Côte d'Azur, BP 4229, 06304 Nice Cedex 4, France e-mail: thevenin@obs-nice.fr
⁵ Anglo-Australian Observatory, PO Box 296, Epping, NSW 1710, Australia
⁶ Special Astrophysical Observatory, Nizhnij Arkhyz, Karachaevo-Cherkesia 369167, Russia
⁷ Sternberg Astronomical Institute, 13 Universitetskij Pr., Moscow 119992, Russia

Received: 28 October 2004
Accepted: 9 February 2005

Abstract

We report the first results of a systematic search near the plane of the Galaxy for so-called very active stars (VAS), which are characterized by a hard X-ray spectrum and activity in the radio domain. Candidates with hard X-ray binary-like spectra have been selected from the Bright ROSAT Source Catalogue in the Zone of Avoidance () and were tentatively identified in GB6/PMM/NVSS radio surveys. Most of them were observed with the ATCA and VLA. Precise radio coordinates have led to unambiguous optical identification for 60 candidates, and a sub-sample of five of them has been observed with the VLT. Also some discovery and confirmatory spectra were obtained with the AAT (4-m) and BTA (6-m). Spectroscopy with moderate dispersion, made with the FORS1 spectrograph of the VLT has revealed two stellar objects (one of them, VASC J1628-41, is definitively a binary VAS), one new AGN and two featureless spectrum sources. One of these objects, VASC J1353-66, shows marginal evidence of proper motion, which, if confirmed, would imply the discovery of a new type of galactic source.