Herschel observations of B1-bS and B1-bN: two first hydrostatic core candidates in the Perseus star-forming cloud

Pezzuto, S.; Elia, D.; Schisano, E.; Strafella, F.; Di Francesco, J.; Sadavoy, S.; André, P.; Benedettini, M.; Bernard, J. P.; di Giorgio, A. M.; Facchini, A.; Hennemann, M.; Hill, T.; Könyves, V.; Molinari, S.; Motte, F.; Nguyen-Luong, Q.; Peretto, N.; Pestalozzi, M.; Polychroni, D.; Rygl, K. L. J.; Saraceno, P.; Schneider, N.; Spinoglio, L.; Testi, L.; Ward-Thompson, D. and White, G. J. (2012). Herschel observations of B1-bS and B1-bN: two first hydrostatic core candidates in the Perseus star-forming cloud. Astronomy & Astrophysics, 547, article no. A54.

DOI: https://doi.org/10.1051/0004-6361/201219501


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.

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