Cold Dark Clouds: The Initial Conditions for Star Formation

Abstract

Cold dark clouds are nearby members of the densest and coldest phase in the galactic interstellar medium, and represent the most accessible sites where stars like our Sun are currently being born. In this review we discuss recent progress in their study, including the newly discovered infrared dark clouds that are likely precursors to stellar clusters. At large scales, dark clouds present filamentary mass distributions with motions dominated by supersonic turbulence. At small, sub-parsec scales, a population of subsonic starless cores provides a unique glimpse of the conditions prior to stellar birth. Recent studies of starless cores reveal a combination of simple physical properties together with a complex chemical structure dominated by the freeze-out of molecules onto cold dust grains. Elucidating this combined structure is both an observational and theoretical challenge whose solution will bring us closer to understanding how molecular gas condenses to form stars.

BIG... 61 pages, 13 figures, to appear in ARAA Vol. 45 in press

References in corpus (14)

• Theory of Star Formation
• The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• Star formation through gravitational collapse and competitive accretion
• The COMPLETE Survey of Star-Forming Regions: Phase I Data
• Bolocam Survey for 1.1 mm Dust Continuum Emission in the c2d Legacy Clouds. II. Ophiuchus
• 2MASS wide field extinction maps - I. The Pipe nebula
• On the internal structure of starless cores. II. A molecular survey of L1498 and L1517B
• The importance of the ortho:para H2 ratio for the deuteration of molecules during pre-protostellar collapse
• Spitzer observations of HH54 and HH7-11: mapping the H2 ortho-to-para ratio in shocked molecular gas
• Spatial mapping of ices in the Oph-F core: A direct measurement of CO depletion and the formation of CO2
• The Thermal Structure of Gas in Pre-Stellar Cores: A Case Study of Barnard 68
• Molecular Line Observations of Infrared Dark Clouds: Seeking the Precursors to Intermediate and Massive Star Formation
• SCUBA polarisation observations of the magnetic fields in the prestellar cores L1498 and L1517B
• Oscillations of starless cores

Cited by in corpus (23)

• Theory of Star Formation
• Filamentary structure of star-forming complexes
• The relation between gas and dust in the Taurus Molecular Cloud
• Molecular Evolution and Star Formation: From Prestellar Cores to Protostellar Cores
• The chemical history of molecules in circumstellar disks. I. Ices
• Survey of ortho-H2D+(1_{1,0}-1_{1,1}) in dense cloud cores
• The Different Structures of the Two Classes of Starless Cores
• The structures of embedded clusters in the Perseus, Serpens and Ophiuchus molecular clouds
• Nitrogen superfractionation in dense cloud cores
• Disk Formation Enabled by Enhanced Resistivity
• A Molecular Line Observation toward Massive Clumps Associated with Infrared Dark Clouds
• The structure of molecular clouds and the universality of the clump mass function
• Protostar Formation in Supersonic Flows: Growth and Collapse of Spherical Cores
• The fractal dimension of star-forming regions at different spatial scales in M33
• Deep Near-Infrared Survey of the Pipe Nebula II: Data, Methods, and Dust Extinction Maps
• Protostar Mass Due to Infall and Dispersal
• The Fractal Distribution of HII Regions in Disk Galaxies
• Molecular Emission Line Formation in Prestellar Cores
• Detection of 6 K gas in Ophiuchus D
• Spitzer Observations of L429: A Near-collapse or Collapsing Starless Core
• The BLAST View of the Star Forming Region in Aquila (ell=45deg,b=0deg)
• Star Formation Near Photodissociation Regions: Detection of a Peculiar Protostar Near Ced 201
• Studies of Dense Cores with ALMA