The initial conditions of isolated star formation - VI. SCUBA mapping of prestellar cores

Abstract

Observations have been carried out with SCUBA at the JCMT of 52 molecular cloud cores that do not contain any sign of protostellar activity. These are all therefore candidate prestellar cores, which are believed to represent the stage of star formation that precedes the formation of a protostar. 29 of the 52 cores were detected at 850 microns at varying levels of signal-to-noise ratio greater than 3 sigma at peak. The detected cores were split into 'bright' cores and `intermediate' cores, depending on their peak flux density at 850 microns. Cores with peak 850 microns flux densities greater than 170 mJy/beam were designated 'bright' (13 cores), while those flux densities below this value were designated 'intermediate' (16 cores). This dividing line corresponds to A_v~50 under typical assumptions. The data are combined with our previously published ISO data, and the physical parameters of the cores, such as density and temperature, are calculated. Detailed fitting of the bright core radial profiles shows that they are not critical Bonnor-Ebert spheres, in agreement with previous findings. However, we find that intermediate cores, such as B68 (which has previously been claimed to be a Bonnor-Ebert sphere), may in fact be consistent with the Bonnor-Ebert criterion, suggesting perhaps that cores pass through such a phase during their evolution. We make rough estimates of core lifetimes based on the statistics of detections and find that the lifetime of a prestellar core is roughly ~3x10^5 years, while that of a bright core is \~1.5x10^5 years. Comparisons with some magnetic and turbulence regulated collapse models show that no model can match all of the data. Models that are tuned to fit the total prestellar core lifetime, do not predict the relative numbers of cores seen at each stage.

23 pages, 52 figures, accepted by MNRAS, alternate PDF w/all figures available from http://www.astro.cf.ac.uk/pub/Derek.Ward-Thompson/publications.html

References in corpus (24)

• The Milky Way in Molecular Clouds: A New Complete CO Survey
• Density, Velocity, and Magnetic Field Structure in Turbulent Molecular Cloud Models
• SCUBA: A common-user submillimetre camera operating on the James Clerk Maxwell Telescope
• Tracing the Mass during Low-Mass Star Formation. II. Modelling the Submillimeter Emission from Pre-Protostellar Cores
• SCUBA Polarization Measurements of the Magnetic Field Strengths in the L183, L1544, and L43 Prestellar Cores
• A Catalogue of Optically Selected Cores
• First Observations of the Magnetic Field Geometry in Pre-stellar Cores
• A SCUBA survey of the NGC 2068/2071 protoclusters
• An empirical model for protostellar collapse
• The dust temperature distribution in prestellar cores
• The initial conditions of isolated star formation. V: ISOPHOT imaging and the temperature and energy balance of pre-stellar cores
• Dynamic cores in hydrostatic disguise
• Consistency of Ambipolar Diffusion Models with Infall in the L1544 Protostellar Core
• Monte Carlo Radiative Transfer in Embedded Prestellar Cores
• On the Timescale for the Formation of Protostellar Cores in Magnetic Interstellar Clouds
• Star Formation in Cold, Spherical, Magnetized Molecular Clouds
• A Far-Infrared Survey of Molecular Cloud Cores
• Far-infrared and molecular line observations of Lynds 183 - studies of cold gas and dust
• The initial conditions of isolated star formation: IV - C18O observations and modelling of the pre-stellar core L1689B
• Envelope Structure of Starless Core L694-2 Derived from a Near-Infrared Extinction Map
• Why do starless cores appear more flattened than protostellar cores?
• Radiative transfer models of non-spherical prestellar cores
• Far infrared observations of pre-protostellar sources in Lynds 183
• Inner Structure of Starless Core L694--2 Derived from Millimeter-Wave Interferometry

Cited by in corpus (154)

• Star Formation in the Milky Way and Nearby Galaxies
• Theory of Star Formation
• The Spitzer c2d Legacy Results: Star Formation Rates and Efficiencies; Evolution and Lifetimes
• Cold Dark Clouds: The Initial Conditions for Star Formation
• MAMBO Mapping of Spitzer c2d Small Clouds and Cores
• High-Mass Star and Massive Cluster Formation in the Milky Way
• The mass function of dense molecular cores and the origin of the IMF
• Bolocam Survey for 1.1 mm Dust Continuum Emission in the c2d Legacy Clouds. I. Perseus
• The earliest phases of high-mass star formation: a 3 square degree millimeter continuum mapping of Cygnus X
• Observing the gas temperature drop in the high-density nucleus of L 1544
• Identifying the Low Luminosity Population of Embedded Protostars in the c2d Observations of Clouds and Cores
• The stellar and sub-stellar IMF of simple and composite populations
• Bolocam Survey for 1.1 mm Dust Continuum Emission in the c2d Legacy Clouds. II. Ophiuchus
• SDC13 infrared dark clouds: Longitudinally collapsing filaments?
• Magnetic Fields in Dark Cloud Cores: Arecibo OH Zeeman Observations
• On the Rapid Collapse and Evolution of Molecular Clouds
• The initial conditions of star formation in the Ophiuchus main cloud: Kinematics of the protocluster condensations
• On the internal structure of starless cores. II. A molecular survey of L1498 and L1517B
• Dense core formation by fragmentation of velocity-coherent filaments in L1517
• Comparing Star Formation on Large Scales in the c2d Legacy Clouds: Bolocam 1.1 mm Dust Continuum Surveys of Serpens, Perseus, and Ophiuchus
• Importance of the Initial Conditions for Star Formation - I. Cloud Evolution and Morphology
• The James Clerk Maxwell Telescope Legacy Survey of Nearby Star-forming Regions in the Gould Belt
• The earliest phases of star formation - A Herschel key project. The thermal structure of low-mass molecular cloud cores
• The Spitzer c2d Survey of Nearby Dense Cores: II: Discovery of a Low Luminosity Object in the "Evolved Starless Core" L1521F
• Reconstructing the density and temperature structure of prestellar cores from $Herschel$ data: A case study for B68 and L1689B
• A census of dense cores in the Taurus L1495 cloud from the Herschel Gould Belt Survey
• Current Star Formation in the Perseus Molecular Cloud: Constraints from Unbiased Submillimeter and Mid-Infrared Surveys
• The Different Structures of the Two Classes of Starless Cores
• The Virial Balance of Clumps and Cores in Molecular Clouds
• First results from the Herschel Gould Belt Survey in Taurus
• The Spitzer c2d Survey of Nearby Dense Cores: I: First Direct Detection of the Embedded Source in IRAM 04191+1522
• Dense core formation in supersonic turbulent converging flows
• A Herschel study of the properties of starless cores in the Polaris Flare dark cloud region using PACS and SPIRE
• Constraints on primordial black holes as dark matter candidates from star formation
• Observational Constraints on Submillimeter Dust Opacity
• Search for starless clumps in the ATLASGAL survey
• An analytic column density profile to fit prestellar cores
• Interferometric Identification of a Pre-Brown Dwarf
• Caught in the act: The Onset of massive star formation
• SCUBA and Spitzer observations of the Taurus molecular cloud - pulling the bull's tail
• Episodic accretion, protostellar radiative feedback, and their role in low-mass star formation
• A Search for Carbon-Chain-Rich Cores in Dark Clouds
• Grain Alignment in Starless Cores
• The relationship between the prestellar core mass function and the stellar initial mass function
• Physical properties of high-mass clumps in different stages of evolution
• The Spitzer survey of interstellar clouds in the Gould Belt. II. The Cepheus Flare observed with IRAC and MIPS
• Radioactive Probes of the Supernova-Contaminated Solar Nebula: Evidence that the Sun was Born in a Cluster
• A SCUBA survey of L1689 - The dog that didn't bark
• Star formation efficiency as a function of metallicity: from star clusters to galaxies
• The dust temperatures of the prestellar cores in the rho Oph main cloud and in other star forming regions: consequences for the core mass function
• The initial conditions of star formation VIII: an observational study of the Ophiuchus cloud L1688 and implications for the prestellar core mass function
• Protostar Formation in Supersonic Flows: Growth and Collapse of Spherical Cores
• The IMF of stellar clusters: effects of accretion and feedback
• Revealing H2D+ depletion and compact structure in starless and protostellar cores with ALMA
• SCUBA polarisation observations of the magnetic fields in the prestellar cores L1498 and L1517B
• The initial conditions of isolated star formation - VII. Spitzer mapping of pre-stellar cores
• Triggered Star Formation
• Initial phases of massive star formation in high infrared extinction clouds. II. Infall and onset of star formation
• Herschel Observations of a Potential Core Forming Clump: Perseus B1-E
• The Origin of the Stellar Mass Distribution and Multiplicity
• The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) 2005: A 4 sq. deg Galactic Plane Survey in Vulpecula (l=59)
• Formation and Collapse of Quiescent Cloud Cores Induced by Dynamic Compressions
• Discovery of interstellar anions in Cepheus star-forming region
• Adiabatic contraction revisited: implications for primordial black holes
• The JCMT Gould Belt Survey: A First Look at Dense Cores in Orion B
• SCUBA observations of the Horsehead Nebula - what did the horse swallow?
• FRagmentation and Evolution of dense cores Judged by ALMA (FREJA). I (Overview). Inner $\sim$1000 au structures of prestellar/protostellar cores in Taurus
• Far-infrared Observations of the Very Low-Luminosity Embedded Source L1521F-IRS in the Taurus Star-Forming Region
• Revealing a detailed mass distribution of a high-density core MC27/L1521F in Taurus with ALMA
• On the mass segregation of stars and brown dwarfs in Taurus
• On the ubiquity of molecular anions in the dense interstellar medium
• The Detection and Characterization of cm Radio Continuum Emission from the Low-mass Protostar L1014-IRS
• Simulating star formation in Ophiuchus
• Formation and evolution of protostellar accretion discs. I. Angular-momentum budget, gravitational self-regulation, and numerical convergence
• Nonlinear Evolution of Gravitational Fragmentation Regulated by Magnetic Fields and Ambipolar Diffusion
• The JCMT Gould Belt Survey: Dense Core Clusters in Orion A
• Detection of Complex Organic Molecules in Young Starless Core L1521E
• Simulations of star formation in Ophiuchus, II: Multiplicity
• Statistics of Core Lifetimes in Numerical Simulations of Turbulent, Magnetically Supercritical Molecular Clouds
• Star formation in molecular cores III. The effect of the turbulent power spectrum
• Initial phases of massive star formation in high infrared extinction clouds. I. Physical parameters
• Detection of 6 K gas in Ophiuchus D
• Fragmentation of star-forming filaments in the X-shape Nebula of the California molecular cloud
• The properties of SCUBA cores in the Perseus molecular cloud: the bias of clump-finding algorithms
• Simulating star formation in molecular cloud cores IV. The role of turbulence and thermodynamics
• CB17: Inferring the dynamical history of a prestellar core with chemo-dynamical models
• Confirmation of the VeLLO L1148-IRS: Star Formation at very low (Column) Density
• Molecular line profiles as diagnostics of protostellar collapse: modelling the `blue asymmetry' in inside-out infall
• Early science with the Large Millimetre Telescope: An LMT/AzTEC 1.1 mm Survey of Dense Cores in the Monoceros R2 Giant Molecular Cloud
• The Spitzer Survey of Interstellar Clouds in the Gould Belt. V. Ophiuchus North Observed with IRAC and MIPS
• A study of the $c$-${\mathrm{C}}_3\mathrm{HD}$/$c$-${\mathrm{C}}_3{\mathrm{H}}_2$ ratio in low-mass star forming regions
• The BLAST Survey of the Vela Molecular Cloud: Physical Properties of the Dense Cores in Vela-D
• The JCMT Gould Belt Survey: Dense Core Clusters in Orion B
• SCUBA Mapping of Spitzer c2d Small Clouds and Cores
• Gas-grain models for interstellar anion chemistry
• Earliest phases of star formation (EPoS): Dust temperature distributions in isolated starless cores
• Methanol Mapping in Cold Cores: Testing Model Predictions
• Using Chemistry to Unveil the Kinematics of Starless Cores: Complex Radial Motions in Barnard 68
• Constraints on primordial black holes from observation of stars in dwarf galaxies
• Initial conditions for star formation in clusters: physical and kinematical structure of the starless core Oph A-N6
• On the effects of solenoidal and compressive turbulence in prestellar cores
• BIMA N2H+ 1-0 mapping observations of L183 -- fragmentation and spin-up in a collapsing, magnetized, rotating, pre-stellar core
• Detection of H2D+ in a massive prestellar core in Orion B
• Synthetic Observations of the Evolution of Starless Cores in a Molecular Cloud Simulation: Comparisons with JCMT Data and Predictions for ALMA
• The Origin of the Rotation Profiles in Star Forming Clouds
• DR 21 South Filament: a Parsec-sized Dense Gas Accretion Flow onto the DR 21 Massive Young Cluster
• A comparison of density structures of a star forming and a non-star-forming globule. DCld303.8-14.2 and Thumbprint Nebula
• Herschel-SPIRE spectroscopy of G29.96-0.02: fitting the full SED
• The initial conditions of isolated star formation -- IX. Akari mapping of an externally heated pre-stellar core
• Prestellar core modeling in the presence of a filament - The dense heart of L1689B
• The initial conditions of isolated star formation - X. A suggested evolutionary diagram for prestellar cores
• An efficient method for determining the chemical evolution of gravitationally collapsing prestellar cores
• Starless Cloud Core L1517B in Envelope Expansion with Core Collapse
• Mass distributions of stars and cores in young groups and clusters
• In search of infall motion in molecular clumps III: HCO+ (1-0) and H13CO+ (1-0) mapping observations toward the confirmed infall sources
• Mapping the prestellar core Ophiuchus D (L1696A) in ammonia
• The immediate environment of the Class 0 protostar VLA1623, on scales of ~50-100 AU, observed at millimetre and centimetre wavelengths
• The Evolution of Cloud Cores and the Formation of Stars
• Polarization of seven MBM clouds at high galactic latitude
• The initial conditions of high-mass star formation: radiative transfer models of IRDCs seen in the Herschel Hi-GAL survey
• Which Part of Dense Cores Feeds Material to Protostars?: The Case of L1489 IRS
• A centrally concentrated sub-solar mass starless core in the Taurus L1495 filamentary complex
• Far-infrared/sub-millimetre properties of pre-stellar cores L1521E, L1521F and L1689B as revealed by the Herschel SPIRE instrument -- I. Central positions
• Magnetic Field Structure of Dense Cores using Spectroscopic Methods
• The Spitzer c2d Survey of Nearby Dense Cores VII: Chemistry and Dynamics in L43
• Evolution and lifetime of transient clumps in the turbulent interstellar medium
• First Sub-pc Sale Mapping of Magnetic Fields in the Vicinity of a Very Low Luminosity Object, L1521F-IRS
• The relative orientation between local magnetic field and Galactic plane in low latitude dark clouds
• In Search for Infall Motion in molecular clumps II: HCO+ (1-0) and HCN (1-0) Observations toward a Sub-sample of Infall Candidates
• Modelling Herschel observations of infrared-dark clouds in the Hi-GAL survey
• Star formation in Chamaeleon I and III: a molecular line study of the starless core population
• Properties of the dense cores and filamentary structures in the Vela C molecular cloud
• From Filaments to Oscillating Starless Cores
• Protostar L1455 IRS1: Rotating Disk Connecting to Filamentary Network
• The Equilibrium Structure of Prolate Magnetized Molecular Cores
• A Catalog of Low-Mass Star-Forming Cores Observed with SHARC-II at 350 microns
• On the internal dynamics of starless cores: stability of starless cores with internal motions and collapse dynamics
• Our Knowledge of High-Mass Star Formation at the Dawn of Herschel
• A VLA search for young protostars embedded in dense cores
• Nobeyama Survey of Inward Motions toward Cores in Orion Identified by SCUBA-2
• Rotation of Two Micron All Sky Survey Clumps in Molecular Clouds
• Capture of primordial black holes in extrasolar systems
• An ALMA search for substructure and fragmentation in starless cores in Orion B North
• Astrophysics in 2005
• Constraining Spatial Densities of Early Ice Formation in Small Dense Molecular Cores from Extinction Maps
• A multi-wavelength study of the star-forming core ahead of HH 80N
• Core formation via filament fragmentation and the impact of ambient pressure on it
• Turbulence and its connection to episodic accretion in binary YSOs
• Formation of Orion Fingers
• On the Scarcity of Dense Cores ($n>10^5$ cm${}^{-3}$) in High Latitude Planck Galactic Cold Clumps
• Extended and Compact Ortho-H${}_2$D${}^{+}$ Structures Close to the Moment of Star-Formation: Evidence from ALMA-ACA Observations in Taurus
• Observational characteristics of dense cores with deeply embedded young protostars
• Why do some cores remain starless ?
• From inter-filamentary gas to filaments and hubs: gas flows in the Mon R2 hub-filament system