Low-Mass Star Formation in the Gum Nebula: The CG 30/31/38 Complex

We present photometric and spectroscopic results for the low mass pre-mainsequence (PMS) stars with spectral types K - M in the cometary globule (CG)30/31/38 complex. We obtained multi-object high resolution spectra for thetargets selected as possible PMS stars from multi-wavelength photometry. Weidentified 11 PMS stars brighter than V = 16.5 with ages < 5 Myr at a distanceof approximately 200 pc. The spatial distribution of the PMS stars, CG clouds,and ionizing sources (O stars and supernova remnants) suggests a possibletriggered origin of the star formation in this region. We confirm the youth ofthe photometrically selected PMS stars using the lithium abundances. The radialvelocities of the low mass PMS stars are consistent with those of the cometaryglobules. Most of the PMS stars show weak Halpha emission with W(Halpha) < 10A. Only 1 out of the 11 PMS stars shows a moderate near-IR excess, whichsuggests a short survival time (t < 5 Myr) of circumstellar disks in this starforming environment. In addition, we find five young late type stars and one Aestar which have no obvious relation to the CG 30/31/38 complex. We also discussa possible scenario of star formation history in the CG 30/31/38 region.Comment: 44 pages, 8 figures, AJ in pres