A Lithium-Survey for Pre-Main Sequence Stars in the Upper Scorpius OB Association

Th. Preibisch, E. Guenther, H. Zinnecker, M. Sterzik, S. Frink, & S. Röser

Astronomy & Astrophysics, 333, 619, (1998)

Abstract

We present the results of an intermediate resolution spectroscopic survey for pre-main sequence (PMS) stars in the Upper Scorpius OB association. In a 160 square-degree area we were able to identify 39 new PMS stars by follow up observations of X-ray selected stars with the multi object spectrograph FLAIR at the UK Schmidt Telescope.

We also investigated the completeness of our X-ray selected sample by observing more than 100 stars that were not detected as X-ray sources, but have proper motions indicating membership to Upper Sco. While the new X-ray selected PMS stars with known proper motions have kinematics consistent with membership, none of the X-ray quiet proper motions candidates is a PMS star. We conclude that our X-ray selected sample of PMS stars seems to be rather complete. For stars in the magnitude interval 11.5 <= B <= 13.5 we derive a conservative lower limit of 75% completeness.

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