A Far-Infrared Survey of Molecular Cloud Cores

Abstract

We present a catalogue of molecular cloud cores drawn from high latitude, medium opacity clouds, using the all-sky IRAS Sky Survey Atlas (ISSA) images at 60 and 100~$\mu$m. The typical column densities of the cores are $N(H_2)\sim 3.8\times 10^{21}$cm${}^{-2}$ and the typical volume densities are $n(H_2)\sim 2\times 10^3$cm${}^{-3}$. They are therefore significantly less dense than many other samples obtained in other ways. Those cloud cores with IRAS point sources are seen to be already forming stars, but this is found to be only a small fraction of the total number of cores. The fraction of the cores in the protostellar stage is used to estimate the prestellar timescale - the time until the formation of a hydrostatically supported protostellar object. We argue, on the basis of a comparison with other samples, that a trend exists for the prestellar lifetime of a cloud core to decrease with the mean column density and number density of the core. We compare this with model predictions and show that the data are consistent with star formation regulated by the ionisation fraction.

arXiv comment13 pages, 7 figures

Cited by in corpus (42)

• The Spitzer c2d Legacy Results: Star Formation Rates and Efficiencies; Evolution and Lifetimes
• The Mass Distribution and Lifetime of Prestellar Cores in Perseus, Serpens, and Ophiuchus
• Star formation in Perseus - V. Outflows detected by HARP
• The initial conditions of isolated star formation - VI. SCUBA mapping of prestellar cores
• An empirical model for protostellar collapse
• Sloan Low-Mass Wide Pairs of Kinematically Equivalent Stars (SLoWPoKES): A Catalog of Very Wide, Low-mass Pairs
• The initial conditions of isolated star formation. V: ISOPHOT imaging and the temperature and energy balance of pre-stellar cores
• Ambipolar-Diffusion Timescale, Star-Formation Timescale, and the Ages of Molecular Clouds: Is There a Discrepancy?
• Testing the universality of the star formation efficiency in dense molecular gas
• Molecular freeze-out as a tracer of the thermal and dynamical evolution of pre- and protostellar cores
• The Formation of Molecular Clouds
• Protostellar Collapse Induced by Compression
• Star formation efficiency as a function of metallicity: from star clusters to galaxies
• An ALMA Search for Substructure, Fragmentation, and Hidden Protostars in Starless Cores in Chamaeleon I
• Protostar Formation in Supersonic Flows: Growth and Collapse of Spherical Cores
• The IMF of stellar clusters: effects of accretion and feedback
• A Search for Close Binaries in the Rho Ophiuchus Star-Forming Region
• JCMT POL-2 and BISTRO Survey observations of magnetic fields in the L1689 molecular cloud
• ALMA Observations of Starless Core Substructure in Ophiuchus
• The JCMT Gould Belt Survey: A First Look at Dense Cores in Orion B
• FRagmentation and Evolution of dense cores Judged by ALMA (FREJA). I (Overview). Inner $\sim$1000 au structures of prestellar/protostellar cores in Taurus
• How Starless Are Starless Cores?
• Spherical Isothermal Self-Similar Shock Flows
• Non-linear dense core formation in the dark cloud L1517
• CARMA-NRO Orion Survey: unbiased survey of dense cores and core mass functions in Orion A
• Submillimeter Studies of Prestellar Cores and Protostars: Probing the Initial Conditions for Protostellar Collapse
• The Evolution of Cloud Cores and the Formation of Stars
• Variation of the Core Lifetime and Fragmentation Scale in Molecular Clouds as an Indication of Ambipolar Diffusion
• ALMA-IMF XVII -- Census and lifetime of high-mass prestellar cores in 14 massive protoclusters
• From Filaments to Oscillating Starless Cores
• The Approach to Collapse of Molecular Clouds
• Externally Fed Star Formation: A Numerical Study
• Distortion of Magnetic Fields in a Starless Core VI: Application of Flux Freezing Model and Core Formation of FeSt 1-457
• Evidence for a Cloud-Cloud Collision in Sh2-233 Triggering the Formation of the High-mass Protostar Object IRAS 05358+3543
• Nobeyama Survey of Inward Motions toward Cores in Orion Identified by SCUBA-2
• An ALMA search for substructure and fragmentation in starless cores in Orion B North
• On the role of magnetic fields in star formation
• Star formation timescale in the molecular filament WB 673
• Spatial Statistics in Star Forming Regions: Is Star Formation Driven By Column Density Alone?
• Physicochemical models: source-tailored or generic?
• Supernova Shocks in Molecular Clouds: Shocks Driven into Dense Cores in IC 443 and 3C 391
• The JCMT BISTRO Survey: The magnetised evolution of star-forming cores in the Ophiuchus Molecular Cloud interpreted using Histograms of Relative Orientation