Monte Carlo radiative transfer in molecular cloud cores

Abstract

We present the results of a three-dimensional Monte Carlo radiative transfer code for starless molecular cloud cores heated by an external isotropic or non-isotropic interstellar radiation field. The code computes the dust temperature distribution inside model clouds with specified but arbitrary density profiles. In particular we examine in detail spherical (Bonnor-Ebert) clouds, axisymmetric and non-axisymmetric toroids, and clouds heated by an external stellar source in addition to the general interstellar field. For these configurations, the code also computes maps of the emergent intensity at different wavelengths and arbitrary viewing angle, that can be compared directly with continuum maps of prestellar cores. In the approximation where the dust temperature is independent of interactions with the gas and where the gas is heated both by collisions with dust grains and ionization by cosmic rays, the temperature distribution of the gas is also calculated. For cloud models with parameters typical of dense cores, the results show that the dust temperature decreases monotonically from a maximum value near the cloud's edge (14-15 K) to a minimum value at the cloud's center (6-7 K). Conversely, the gas temperature varies in a similar range, but, due to efficient dust-gas coupling in the inner regions and inefficient cosmic-ray heating in the outer regions, the gradient is non-monotonic and the gas temperature reaches a maximum value at intermediate radii. The emission computed for these models (at 350 micron and 1.3 mm) shows that deviations from spherical symmetry in the density and/or temperature distributions are generally reduced in the simulated intensity maps (even without beam convolution), especially at the longer wavelengths.

12 pages, 6 figures. Astronomy and Astrophysics, in press

References in corpus (15)

• Molecular ions in L1544. II. The ionization degree
• Tracing the Mass during Low-Mass Star Formation. II. Modelling the Submillimeter Emission from Pre-Protostellar Cores
• Radiative Equilibrium and Temperature Correction in Monte Carlo Radiation Transfer
• Tracing the Mass during Low-Mass Star Formation. I. Submillimeter Continuum Observations
• First Observations of the Magnetic Field Geometry in Pre-stellar Cores
• Molecular ions in L1544. I. Kinematics
• 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
• The structure and stability of molecular cloud cores in external radiation fields
• Magnetic Fields and the Triaxiality of Molecular Cloud Cores
• Dust emissivity in the Submm/Mm: SCUBA and SIMBA observations of Barnard 68
• Monte Carlo Radiative Transfer in Embedded Prestellar Cores
• Massive Quiescent Cores in Orion. I. Temperature Structure
• The Intrinsic Shapes of Molecular Cloud Fragments over a Range of Length Scales
• Singular Isothermal Disks: II. Nonaxisymmetric Bifurcations and Equilibria

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• Observations of L1521F: a highly evolved starless core
• Modeling the Physical Structure of the Low Density Pre-protostellar Core Lynds 1498
• BLAST: The Mass Function, Lifetimes, and Properties of Intermediate Mass Cores from a 50 Square Degree Submillimeter Galactic Survey in Vela (l = ~265)
• Radiative Transfer and Starless Cores
• Dark cloud cores and gravitational decoupling from turbulent flows
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• Density and Temperature Structure of TMC-1C from 450 and 850 micron Maps
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• Polarized dust emission of magnetized molecular cloud cores
• Radiative transfer models of non-spherical prestellar cores
• Earliest phases of star formation (EPoS): Dust temperature distributions in isolated starless cores
• The Gas Temperature of Starless Cores in Perseus
• Some like it cold: molecular emission and effective dust temperatures of dense cores in the Pipe Nebula
• The Evolution of Cloud Cores and the Formation of Stars
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• ALMA-IMF XVI: Mass-averaged temperature of cores and protostellar luminosities in the ALMA-IMF protoclusters
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