Prestellar Cores in Turbulent Clouds: Properties of Critical Cores

Abstract

A fraction of the dense cores within a turbulent molecular cloud will eventually collapse to form stars. Identifying the physical criteria for instability and analyzing critical core properties is therefore necessary to star formation theory. Here we quantify the characteristics of an ensemble of "critical cores" on the verge of collapse. This critical epoch was identified in a companion paper, which followed the dynamical evolution of prestellar cores in numerical simulations of turbulent, self-gravitating clouds. We find that radial profiles of density and turbulent velocity dispersion in individual critical cores are consistent with our new model for turbulent equilibrium spheres (TESs). While a global linewidth-size relation exists for a cloud with given size and Mach number, the turbulent scaling relations around each core exhibit significant variations. As a result, there is no single density threshold for collapse; instead, cores collapse at a range of densities determined by the local sonic scale and gravitational potential environment. The critical cores in our simulations are mostly transonic; we do not find either purely thermal or highly turbulent cores. In our low Mach number model which better resolves the characteristic mass and sonic scales, we find marginal evidence that the core mass function (CMF) of critical cores peaks around a characteristic mass scale associated with the large-scale cloud properties. We highlight the importance of constructing the CMF at the critical time for the purpose of testing gravoturbulent fragmentation theories, and derive the resolution requirements to unambiguously identify the peak of the CMF.

28 pages, 13 figures, accepted for publication in ApJ; replaced with the accepted version

References in corpus (34)

• Theory of Star Formation
• Cold Dark Clouds: The Initial Conditions for Star Formation
• Analytical theory for the initial mass function: CO clumps and prestellar cores
• The relation between gas and dust in the Taurus Molecular Cloud
• Magnetically Regulated Star Formation in 3D: The Case of Taurus Molecular Cloud Complex
• Properties of the dense core population in Orion B as seen by the Herschel Gould Belt survey
• Formation of Magnetized Prestellar Cores with Ambipolar Diffusion and Turbulence
• The Green Bank Ammonia Survey: Dense Cores Under Pressure in Orion A
• Protostellar Outflows and Radiative Feedback from Massive Stars. II. Feedback, Star Formation Efficiency, and Outflow Broadening
• CARMA Large Area Star Formation Survey: Structure and Kinematics of Dense Gas in Serpens Main
• The ALMA Survey of 70 $\mu$m Dark High-mass Clumps in Early Stages (ASHES). IX. Physical Properties and Spatial Distribution of Cores in IRDCs
• Protostar Formation in Supersonic Flows: Growth and Collapse of Spherical Cores
• From the CMF to the IMF: Beyond the Core-Collapse Model
• ALMA-IMF. V. Prestellar and protostellar core populations in the W43 cloud complex
• Physical properties of the ambient medium and of dense cores in the Perseus star-forming region derived from Herschel Gould Belt Survey observations
• Prestellar Core Formation, Evolution, and Accretion from Gravitational Fragmentation in Turbulent Converging Flows
• The ALMA Survey of 70 μm Dark High-mass Clumps in Early Stages (ASHES). VIII. Dynamics of Embedded Dense Cores
• Turbulence, Coherence and Collapse: Three Phases for Core Evolution
• The JCMT and Herschel Gould Belt Surveys: A comparison of SCUBA-2 and Herschel data of dense cores in the Taurus dark cloud L1495
• The core population and kinematics of a massive clump at early stages: an ALMA view
• Can magnetized turbulence set the mass scale of stars?
• Herschel Gould Belt Survey Observations of Dense Cores in the Cepheus Flare Clouds
• The JCMT Gould Belt Survey: First results from SCUBA-2 observations of the Cepheus Flare Region
• The Green Bank Ammonia Survey: A Virial Analysis of Gould Belt Clouds in Data Release 1
• The Shapes of Molecular Cloud Cores in Orion
• The census of dense cores in the Serpens region from the Herschel Gould Belt Survey
• The Green Bank Ammonia Survey: Observations of Hierarchical Dense Gas Structures in Cepheus-L1251
• Transition from Coherent Cores to Surrounding Cloud in L1688
• TRAO Survey of the nearby filamentary molecular clouds, the universal nursery of stars (TRAO FUNS). II. Filaments and Dense cores in IC 5146
• CARMA Large Area Star Formation Survey: Dense Gas in the Young L1451 Region of Perseus
• TRAO Survey of Nearby Filamentary Molecular clouds, the Universal Nursery of Stars (TRAO FUNS) I. Dynamics and Chemistry of L1478 in the California Molecular Cloud
• Effects of stellar feedback on cores in STARFORGE
• Prestellar Cores in Turbulent Clouds: Numerical Modeling and Evolution to Collapse
• Theory of Turbulent Equilibrium Spheres with Power-Law Linewidth-Size Relation