Star formation in the Vela Molecular Ridge. Large scale mapping of cloud D in the mm continuum

Abstract

The Vela Molecular Ridge is one of the nearest intermediate-mass star forming regions, located within the galactic plane and outside the solar circle. Cloud D, in particular, hosts a number of small embedded young clusters. We present the results of a large-scale map in the dust continuum at 1.2 mm of a ~ 1deg x 1deg area within cloud D. The main aim of the observations was to obtain a complete census of cluster-forming cores and isolated (both high- and low-mass) young stellar objects in early evolutionary phases. The bolometer array SIMBA at SEST was used to map the dust emission in the region with a typical sensitivity of ~ 20 mJy/beam. This allows a mass sensitivity of ~ 0.2 Msun. The resolution is 24 arcsec, corresponding to ~ 0.08 pc, roughly the radius of a typical young embedded cluster in the region. The continuum map is also compared to a large scale map of CO(1-0) integrated emission. Using the CLUMPFIND algorithm, a robust sample of 29 cores has been obtained, spanning the size range 0.03 - 0.25 pc and the mass range 0.4 - 88 Msun. The most massive cores are associated both with red IRAS sources and with embedded young clusters, and coincide with CO(1-0) integrated emission peaks. The cores are distributed according to a mass spectrum ~ M^{-alpha} and a mass-versus-size relation ~ D^{x}, with alpha ~ 1.45 - 1.9 and x ~ 1.1 - 1.7. They appear to originate in the fragmentation of gas filaments seen in CO(1-0) emission and their formation is probably induced by expanding shells of gas. The core mass spectrum is flatter than the Initial Mass Function of the associated clusters in the same mass range, suggesting further fragmentation within the most massive cores. A threshold A_V ~ 12 mag seems to be required for the onset of star formation in the gas.

13 pages, 11 figures, to be published in Astronomy and Astrophysics

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Cited by in corpus (21)

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• The New EXor Outburst of ESO-H-alpha~99 observed by Gaia ATLAS and TESS
• Massive Stars and their Supernovae
• Dense cores and star formation in the giant molecular cloud Vela~C
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• The Spitzer-IRAC Point Source Catalog of the Vela-D Cloud
• Investigating the temporal domain of massive ionized jets - I. A pilot study
• Spitzer-MIPS survey of the young stellar content in the Vela Molecular Cloud-D
• The YSO Population in the Vela-D Molecular Cloud
• Pre-Main Sequence variables in the VMR-D : identification of T Tauri-like accreting protostars through Spitzer-IRAC variability
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• The BLAST Survey of the Vela Molecular Cloud: Dynamical Properties of the Dense Cores in Vela-D
• Testing circumstellar disk lifetimes in young embedded clusters associated with the Vela Molecular Ridge
• A spectral line survey of the starless and proto-stellar cores detected by BLAST toward the Vela-D molecular cloud
• Star forming regions linked to RCW78 and the discovery of a new IR bubble
• Molecules, dust, and protostars in NGC 3503