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Published April 2010 | Published
Journal Article Open

Ultraviolet-selected field and pre-main-sequence stars toward taurus and upper scorpius


We have carried out a Galaxy Evolution Explorer (GALEX) Cycle 1 guest investigator program covering 56 deg^2 near the Taurus T association and 12 deg^2 along the northern edge of the Upper Scorpius OB association. We combined photometry in the GALEX far-ultraviolet and near-ultraviolet bands with data from the Two Micron All Sky Survey to identify candidate young (≾ 100 Myr old) stars as those with an ultraviolet excess relative to older main-sequence stars. Follow-up spectroscopy of a partial sample of these candidates suggests five new members of Taurus, with 8-20 expected from additional observations, and five new members of Upper Scorpius, with three to six expected from additional observations. These candidate new members appear to represent a distributed, non-clustered population in either region, although our sample statistics are as of yet too poor to constrain the nature or extent of this population. Rather, our study demonstrates the ability of GALEX observations to identify young stellar populations distributed over a wide area of the sky. We also highlight the necessity of a better understanding of the Galactic ultraviolet source population to support similar investigations. In particular, we report a large population of stars with an ultraviolet excess but no optical indicators of stellar activity or accretion, and briefly argue against several interpretations of these sources.

Additional Information

© 2010 The American Astronomical Society. Received 2009 September 21; accepted 2010 January 8; published 2010 February 25. We thank John Carpenter for his discussions of the initial GALEX proposal and for his helpful comments on the manuscript. We also thank Karl Forster for his help planning the observations, Ted Wyder for his advice on GALEX data reduction, and Adam Kraus for his proper motion analysis.

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Published - Findeisen2010p7397Astron_J.pdf


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