Astron. Astrophys. 363, L25-L28 (2000)

1. Introduction

Zuckerman & Webb (2000) sketch a picture of the recent star formation history of the solar neighbourhood in which 10-40 million years ago an ensemble of molecular clouds were forming stars at a modest rate near the present position of the Sun. About 10 Myrs ago, the most massive of these newly formed stars exploded as a supernova, terminating the star formation episode and generating the very low density region seen in most directions from the present Sun (Welsh et al. 1998). This scenario can not only explain the presence of young stellar groups close to the earth, but also explains how the  Pic moving group can be so young (20 Myr; Barrado y Navascués et al. 1999), and yet so close. However, currently this scenario is largely speculative.

HD 199143 is a poorly studied bright (V = ) star in the constellation of Capricornius. It has been classified as F8V in the Michigan Spectral Survey (Houk & Smith-Moore 1988), after an initial classification of G0 by Cannon & Mayall (1949). The star would be completely inconspicuous, if it hadn't been detected as a bright extreme-ultraviolet source by the ROSAT (2RE J205547-170622) and Extreme Ultraviolet Explorer (2EUVE J2055-17.1) missions (Pounds et al. 1993; Malina et al. 1994; Pye et al. 1995; Bowyer et al. 1996).

In this Letter we present new optical and ultraviolet spectroscopy of HD 199143 and show that it is a variable and rapidly rotating F8V star. We infer that all characteristics of the HD 199143 system can be explained by assuming that it is a binary system, in which the primary has been spun up by accretion of mass from a low-mass companion. Its association with a previously studied T Tauri-like system (BD-17^o6128) suggests that these two stars could be the first two members of a close (48 pc) new region of recent star formation and may provide compelling support for the star formation history of the solar neighbourhood outlined in the first paragraph.

© European Southern Observatory (ESO) 2000

Online publication: December 11, 2000
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