A study of dense molecular gas and star formation toward the Vela Molecular Ridge with NANTEN

Abstract

New observations of the J = 1-0 12CO, 13CO, and C18O emission lines have been extensively made toward the Vela Molecular Ridge (VMR) with NANTEN. The most prominent cloud is the giant molecular cloud, corresponding to the VMR-C region (Vela C). The present C18O distribution has been identified as 29 clouds. Among them, the most massive one is included in Vela C, having a total mass of ∼ 4.4 × 104 M(Fish eye sign). The rest of them are smaller C18O clouds of 102-103 M(Fish eye sign). Star formation in the region is almost exclusively occurring in the C18O clouds. The luminosities of the associated protostellar IRAS sources range from 5 L(Fish eye sign) to 1.1 × 104 L(Fish eye sign), and the luminosity distribution is found to be well represented by the relation dNstar/dLIR ∝ L-1.65±014IR. We find that the ratios of the total luminosity of the sources associated with given C18O clouds to the cloud masses are significantly enhanced for those clouds associated with H II regions by an order of magnitude. This is interpreted as meaning that the formation of massive stars is enhanced due to the effects of H II regions, as is consistent with the preceding work. We have also newly found molecular outflow toward IRAS 08588-4347 as well as five possible candidates for outflows.