A Large Spectroscopic Survey for Young Low-Mass Members of the Upper Scorpius OB Association
Abstract
We present the results of a large intermediate-resolution spectroscopic survey for pre-main-sequence (PMS) stars in the Upper Scorpius OB association, the nearest region of recent massive star formation. Utilizing the 2dF multiobject spectrograph at the Anglo-Australian Telescope, we obtained spectra of 576 stars with magnitudes 12.5<=R<=16.5 in a 6 deg2 area in Upper Scorpius. Among these objects we were able to identify 98 new PMS stars, nearly all of them M-type stars, by their strong lithium absorption lines. We place the new PMS stars into the H-R diagram and find that their ages agree well with the mean age of 5 Myr determined in our earlier investigation based on a smaller sample of stars. The number of low-mass (0.1 Msolar<~M*<~0.5 Msolar) members is at least as high as expected from the known number of high-mass (M*>~3 Msolar) association members and from recent determinations of the field star initial mass function. Thus, there is no deficit of low-mass stars in Upper Scorpius.
- Publication:
-
The Astronomical Journal
- Pub Date:
- February 2001
- DOI:
- 10.1086/318774
- Bibcode:
- 2001AJ....121.1040P
- Keywords:
-
- Galaxy: Open Clusters and Associations: Individual: Name: Scorpius-Centaurus;
- stars: mass function;
- Stars: Pre-Main-Sequence