Planck early results. XXII. The submillimetre properties of a sample of Galactic cold clumps
Publication date: 01 December 2011
Authors: Planck Collaboration
Journal: Astronomy & Astrophysics
Copyright: ESO, 2011
We perform a detailed investigation of sources from the Cold Cores Catalogue of Planck Objects (C3PO). Our goal is to probe the reliability of the detections, validate the separation between warm and cold dust emission components, provide the first glimpse at the nature, internal morphology and physical characterictics of the Planck-detected sources. We focus on a sub-sample of ten sources from the C3PO list, selected to sample different environments, from high latitude cirrus to nearby (150pc) and remote (2kpc) molecular complexes. We present Planck surface brightness maps and derive the dust temperature, emissivity spectral index, and column densities of the fields. With the help of higher resolution Herschel and AKARI continuum observations and molecular line data, we investigate the morphology of the sources and the properties of the substructures at scales below the Planck beam size. The cold clumps detected by Planck are found to be located on large-scale filamentary (or cometary) structures that extend up to 20pc in the remote sources. The thickness of these filaments ranges between 0.3 and 3pc, for column densities NH2 ~ 0.1 to 1.6 × 1022 cm-2, and with linear mass density covering a broad range, between 15 and 400 Mo pc-1. The dust temperatures are low (between 10 and 15K) and the Planck cold clumps correspond to local minima of the line-of-sight averaged dust temperature in these fields. These low temperatures are confirmed when AKARI and Herschel data are added to the spectral energy distributions. Herschel data reveal a wealth of substructure within the Planck cold clumps. In all cases (except two sources harbouring young stellar objects), the substructures are found to be colder, with temperatures as low as 7K. Molecular line observations provide gas column densities which are consistent with those inferred from the dust.
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