Low Mass Star Formation in the Gum Nebula: The CG~30/31/38 complex

Abstract

We present photometric and spectroscopic results for the low mass pre-main sequence (PMS) stars with spectral types K - M in the cometary globule (CG) 30/31/38 complex. We obtained multi-object high resolution spectra for the targets selected as possible PMS stars from multi-wavelength photometry. We identified 11 PMS stars brighter than V = 16.5 with ages < 5 Myr at a distance of approximately 200 pc. The spatial distribution of the PMS stars, CG clouds, and ionizing sources (O stars and supernova remnants) suggests a possible triggered origin of the star formation in this region. We confirm the youth of the photometrically selected PMS stars using the lithium abundances. The radial velocities of the low mass PMS stars are consistent with those of the cometary globules. Most of the PMS stars show weak Halpha emission with W(Halpha) < 10 A. Only 1 out of the 11 PMS stars shows a moderate near-IR excess, which suggests a short survival time (t < 5 Myr) of circumstellar disks in this star forming environment. In addition, we find five young late type stars and one Ae star which have no obvious relation to the CG 30/31/38 complex. We also discuss a possible scenario of star formation history in the CG 30/31/38 region.

arXiv comment44 pages, 8 figures, AJ in press

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