The Properties of Planck Galactic Cold Clumps in the L1495 Dark Cloud
2018
Planck Galactic Cold Clumps (PGCCs) possibly represent the early stages of star formation. To understand better
the properties of PGCCs, we studied 16 PGCCs in the L1495 cloud with molecular lines and continuum data from
Herschel, JCMT/SCUBA-2, and the PMO 13.7 m telescope. Thirty dense cores were identified in 16 PGCCs from
2D Gaussian fitting. The dense cores have dust temperatures of Td = 11–14 K, and H2 column densities of NH2
= (0.36–2.5) × 1022 cm−2
. We found that not all PGCCs contain prestellar objects. In general, the dense cores in
PGCCs are usually at their earliest evolutionary stages. All the dense cores have non-thermal velocity dispersions
larger than the thermal velocity dispersions from molecular line data, suggesting that the dense cores may be
turbulence-dominated. We have calculated the virial parameter α and found that 14 of the dense cores have α <2,
while 16 of the dense cores have α >2. This suggests that some of the dense cores are not bound in the absence of
external pressure and magnetic fields. The column density profiles of dense cores were fitted. The sizes of the flat
regions and core radii decrease with the evolution of dense cores. CO depletion was found to occur in all the dense
cores, but is more significant in prestellar core candidates than in protostellar or starless cores. The protostellar
cores inside the PGCCs are still at a very early evolutionary stage, sharing similar physical and chemical properties
with the prestellar core candidates.
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