PROBING THE EARLIEST PHASES OF STAR FORMATION: AN HERSCHEL PHOTOMETRIC SURVEY OF NEARBY MOLECULAR CLOUDS

摘要

The study of the earliest stages of star formation in molecular clouds is one of the fields that should benefit most from Herschel and ALMA. Improving our understanding of these deeply embedded stages is crucial to gain insight into the origin of stellar masses, multiple systems, and protoplanetary disks. As prestellar cores and young protostars emit the bulk of their luminosity between ～80 and ～500 μm, the two imaging instruments of Herschel (SPIRE and PACS) are uniquely suited finding and characterizing such objects in the nearby cloud complexes of the Gould Belt (d < 0.5 kpc). Here, we summarize the case for an Herschel guaranteed-time key project aimed at a wide-field SPIRE/PACS survey of the densest part of the Gould Belt. This Herschel photometric survey will provide, for the first time, the mass and luminosity functions for complete samples of thousands of cold condensations down to the proto-brown dwarf regime. Thanks to its large spatial dynamic range, it will probe the link between diffuse ISM structures and compact self-gravitating condensations, thereby setting strong constraints on possible core formation mechanism(s). The Herschel survey discussed in this paper will also provide a unique database, including in the Southern hemisphere, for follow-up high-resolution molecular line/dust continuum studies with ALMA.