Volume 547, November 2012
|Number of page(s)||13|
|Section||Interstellar and circumstellar matter|
|Published online||25 October 2012|
Herschel observations of B1-bS and B1-bN: two first hydrostatic core candidates in the Perseus star-forming cloud⋆,⋆⋆
IAPS – INAF, via Fosso del Cavaliere 100,
2 Dipartimento di Fisica, Università del Salento, CP 193, 73100 Lecce, Italy
3 National Research Council Canada, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria BC, V9E 2E7, Canada
4 Department of Physics and Astronomy, University of Victoria, PO Box 355, STN CSC, Victoria BC, V8W 3P6, Canada
5 Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot, IRFU/Service d’Astrophysique, CEA Saclay, 91191 Gif-sur-Yvette, France
6 CESR, Observatoire Midi-Pyrénées (CNRS-UPS), Université de Toulouse, BP 44346, 31028 Toulouse, France
7 Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8, Canada
8 LAB/OASU-UMR5804, CNRS – University of Bordeaux, 33270 Floirac, France
9 ESO, Karl Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
10 Jeremiah Horrocks Institute, University of Central Lancashire, PR1 2HE, UK
11 Department of Physics and Astrophysics, Open University, Walton Hall, Milton Keynes MK7 6AA, UK
12 14 Rutherford Appleton Laboratory, Chilton OX11 0QX, UK
Accepted: 24 September 2012
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.
Key words: stars: protostars / stars: individual: [HKM99] B1-bS / stars: individual: [HKM99] B1-bN / stars: individual: [EYG2006] Bolo 81 / stars: individual: [EDJ2009] 295
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
© ESO, 2012
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