The BLAST Survey of the Vela Molecular Cloud: Dynamical Properties of the Dense Cores in Vela-D

TL;DR

This study investigates the dynamical properties of dense cores in the Vela-D region of the Vela Molecular Ridge, revealing that many cores are likely gravitationally bound when considering high-density tracers, which has implications for star formation processes.

Contribution

It provides a detailed analysis of the dynamical state of dense cores in Vela-D using BLAST data and compares it with 13CO observations, highlighting the importance of high-density tracers in assessing core binding.

Findings

Most proto-stellar cores are gravitationally bound when scaled with high-density tracers.

The internal pressure estimates depend on the choice of linewidths from different molecular tracers.

External confinement mechanisms, such as magnetic fields, may be necessary to bind some cores.

Abstract

The Vela-D region, according to the nomenclature given by Murphy & May (1991), of the star forming complex known as the Vela Molecular Ridge (VMR), has been recently analyzed in details by Olmi et al. (2009), who studied the physical properties of 141 pre- and proto-stellar cold dust cores, detected by the ``Balloon-borne Large-Aperture Submillimeter Telescope'' (BLAST) during a much larger (55 sq. degree) Galactic Plane survey encompassing the whole VMR. This survey's primary goal was to identify the coldest, dense dust cores possibly associated with the earliest phases of star formation. In this work, the dynamical state of the Vela-D cores is analyzed. Comparison to dynamical masses of a sub-sample of the Vela-D cores estimated from the 13CO survey of Elia et al. (2007), is complicated by the fact that the 13CO linewidths are likely to trace the lower density intercore material, in addition to the dense gas associated with the compact cores observed by BLAST. In fact, the total internal pressure of these cores, if estimated using the 13CO linewidths, appears to be higher than the cloud ambient pressure. If this were the case, then self-gravity and surface pressure would be insufficient to bind these cores and an additional source of external confinement (e.g., magnetic field pressure) would be required. However, if one attempts to scale down the 13CO linewidths, according to the observations of high-density tracers in a small sample of sources, then most proto-stellar cores would result effectively gravitationally bound.