Herschel observations of B1-bS and B1-bN: two first hydrostatic core candidates in the Perseus star-forming cloud
Hill, T.;
White, G. J.;
Könyves, V.;
Rygl, K. L. J.;
Testi, L.;
Schneider, N.;
Di Francesco, J.;
Peretto, N.;
Benedettini, M.;
Elia, D.;
Motte, F.;
Pezzuto, S.;
Schisano, E.;
Spinoglio, L.;
Ward-Thompson, D.;
Polychroni, D.;
Hennemann, M.;
André, P.;
Molinari, S.;
Saraceno, P.;
Sadavoy, S.;
Pestalozzi, M.;
di Giorgio, A. M.;
Bernard, J. P.;
Nguyen-Luong, Q.;
Strafella, F.;
Facchini, A.
Italy, Canada, France, Germany, United Kingdom
Abstract
We report far-infrared Herschel observations obtained between 70 μm and 500 μm of two star-forming dusty condensations, [HKM99] B1-bS and [HKM99] B1-bN, in the B1 region of the Perseus star-forming cloud. In the western part of the Perseus cloud, B1-bS is the only source detected in all six PACS and SPIRE photometric bands, but it is not visible in the Spitzer map at 24 μm. B1-bN is clearly detected between 100 μm and 250 μm. We have fitted the spectral energy distributions of these sources to derive their physical properties, and find that a simple greybody model fails to reproduce the observed spectral energy distributions. At least a two-component model is required, consisting of a central source surrounded by a dusty envelope. The properties derived from the fit, however, suggest that the central source is not a Class 0 object. We then conclude that while B1-bS and B1-bN appear to be more evolved than a pre-stellar core, the best-fit models suggest that their central objects are younger than a Class 0 source. Hence, they may be good candidates to be examples of the first hydrostatic core phase. The projected distance between B1-bS and B1-bN is a few Jeans lengths. If their physical separation is close to this value, this pair would allow studying the mutual interactions between two forming stars at a very early stage of their evolution.
Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendices are available in electronic form at
http://www.aanda.org
2012
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Astronomy and Astrophysics
Herschel
101
