A Distributed Population of Low-Mass Pre-Main-Sequence Stars near the Taurus Molecular Clouds

Abstract

We present a drift-scan survey covering a ~5° × 50° region toward the southern portion of the Taurus-Auriga molecular cloud. Data taken in the B,R,I filters with the Quest-2 camera on the Palomar 48 inch (1.2 m) Samuel Oschin Telescope were combined with Two Micron All Sky Survey near-infrared photometry to select candidate young stars. Follow-up optical spectroscopy of 190 candidates led to the identification of 42 new low-mass pre-main-sequence stars with spectral types M4-M8, of which approximately half exhibit surface gravity signatures similar to known Taurus stars, while the other half exhibit surface gravity signatures similar to members of the somewhat older Upper Scorpius, TW Hya, and β Pic associations. The pre-main-sequence stars are spread over ~35°, and many are located well outside of previously explored regions. From assessment of the spatial and proper-motion distributions, we argue that the new pre-main-sequence stars identified far from the clouds cannot have originated from the vicinity of the 1-2 Myr old subclusters that contain the bulk of the identified Taurus members but instead represent a newly identified area of recent star formation near the clouds.

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