* Astronomy

Blobrana · L

RE: Vela C

Blobrana · L

Flying along the Vela ridge

A beautiful blue butterfly flutters towards a nest of warm dust and gas, above an intricate network of cool filaments in this image of the Vela C region by ESA's Herschel space observatory.
Vela C is the most massive of the four parts of the Vela complex, a massive star nursery just 2300 light-years from the Sun. It is an ideal natural laboratory for us to study the birth of stars.
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Blobrana · L

Title: The Herschel view of the on-going star formation in the Vela-C molecular cloud
Authors: T.Giannini, D. Elia, D. Lorenzetti, S. Molinari, F. Motte, E. Schisano, S. Pezzuto, M. Pestalozzi, A. M. Di Giorgio, P. Andrè, T. Hill, M. Benedettini, S. Bontemps, J. Di Francesco, C. Fallscheer, M. Hennemann, J. Kirk, V. Minier, Q. Nguyen Luong, D. Polychroni, K.L.J. Rygl, P. Saraceno, N. Schneider, L. Spinoglio, L. Testi, D. Ward-Thompson, G. J. White

As part of the Herschel guaranteed time key program 'HOBYS', we present the photometric survey of the star forming region Vela-C, one of the nearest sites of low-to-high-mass star formation in the Galactic plane. Vela-C has been observed with PACS and SPIRE in parallel mode between 70 um and 500 um over an area of about 3 square degrees. A photometric catalogue has been extracted from the detections in each band, using a threshold of 5 sigma over the local background. Out of this catalogue we have selected a robust sub-sample of 268 sources, of which 75% are cloud clumps and 25% are cores. Their Spectral Energy Distributions (SEDs) have been fitted with a modified black body function. We classify 48 sources as protostellar and 218 as starless. For two further sources, we do not provide a secure classification, but suggest they are Class 0 protostars.
From SED fitting we have derived key physical parameters. Protostellar sources are in general warmer and more compact than starless sources. Both these evidences can be ascribed to the presence of an internal source(s) of moderate heating, which also causes a temperature gradient and hence a more peaked intensity distribution.
Moreover, the reduced dimensions of protostellar sources may indicate that they will not fragment further. A virial analysis of the starless sources gives an upper limit of 90% for the sources gravitationally bound and therefore prestellar. We fit a power law N(logM) prop M^-1.1 to the linear portion of the mass distribution of prestellar sources. This is in between that typical of CO clumps and those of cores in nearby star-forming regions. We interpret this as a result of the inhomogeneity of our sample, which is composed of comparable fractions of clumps and cores.

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Blobrana · L

Title: HOBYS' view of Vela C and W48: a ridge and a mini-starburst
Authors: T. Hill, Q. Nguyen Luong, F. Motte, P. Didelon, V. Minier, the HOBYS consortium

We present recent results from the Herschel HOBYS guaranteed time key program of the Vela C and W48 star-forming complexes. We examine the column density distribution in Vela C, in particular focusing on the cloud structure using probability distribution functions, and characterise the star formation efficiency in W48.

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