The census of dense cores in the Serpens region from the Herschel Gould Belt Survey

Abstract

The Herschel Gould Belt survey mapped the nearby (d < 500 pc) star-forming regions to understand better how the prestellar phase influences the star formation process. Here we report a complete census of dense cores in a ∼ 15 deg 2 area of the Serpens star-forming region located between d ∼ 420 pc and 484 pc. The PACS and SPIRE cameras imaged this cloud from 70 µm to 500 µm. With the multi-wavelength source extraction algorithm getsources , we extract 833 sources, of which 709 are starless cores and 124 are candidate proto-stellar cores. We obtain temperatures and masses for all the sample, classifying the starless cores in 604 prestellar cores and 105 unbound cores. Our census of sources is 80% complete for M > 0.8 M overall. We produce the core mass function (CMF) and compare it with the initial mass function (IMF). The prestellar CMF is consistent with log-normal trend up to ∼ 2 M , after which it follows a power-law with slope of −2.05 ± 0.34. The tail of its CMF is steeper but still compatible with the IMF for the region we studied in this work. We also extract the filaments network of the Serpens region, finding that 81% of prestellar cores lie on filamentary structures. The spatial association between cores and filamentary structure supports the paradigm, suggested by other Herschel observations, that prestellar cores mostly form on filaments. Serpens is confirmed to be a young, low-mass and active star-forming region.