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We present describe a new computer code that solves the radiative transfer problem on multi-resolution grids. If the cloud model is from an MHD simulation on a regular cartesian grid, criteria based for example on local density or velocity…

Astrophysics · Physics 2009-11-10 M. Juvela , P. Padoan

Pre-stellar cores are the first steps in the process of star and planet formation. However, the dynamical and chemical evolution of pre-stellar cores is still not well understood. We aim at estimating the central density of the pre-stellar…

Astrophysics of Galaxies · Physics 2025-02-05 S. Spezzano , E. Redaelli , P. Caselli , O. Sipilä , J. Harju , F. Lique , D. Arzoumanian , J. E. Pineda , F. Wyrowski , A. Belloche

Interactions between clouds and radiation are at the root of many difficulties in numerically predicting future weather and climate and in retrieving the state of the atmosphere from remote sensing observations. The large range of issues…

We study the multi-dimensional radiative transfer phenomena using the ISMC scheme, in both gray and multi-frequency problems. Implicit Monte-Carlo (IMC) schemes have been in use for five decades. The basic algorithm yields teleportation…

Computational Physics · Physics 2022-01-06 Elad Steinberg , Shay I. Heizler

A new code for evaluation of light absorption and scattering by interstellar dust grains is presented. The radiative transfer problem is solved using ray-tracing algorithm in a self-consistent and highly efficient way. The code demonstrates…

Astrophysics · Physics 2007-05-23 D. Semionov , V. Vansevicius

Constraints on the density and thermal 3D structure of the dense molecular cloud core Rho Oph D are derived from a detailed 3D radiative transfer modeling. Two ISOCAM images at 7 and 15 micron are fitted simultaneously by representing the…

Astrophysics · Physics 2009-11-10 J. Steinacker , A. Bacmann , Th. Henning , R. Klessen , M. Stickel

Stars form in cold dense cores showing subsonic velocity dispersions. The parental molecular clouds display higher temperatures and supersonic velocity dispersions. The transition from core to cloud has been observed in velocity dispersion,…

We analyze a three-dimensional smoothed particle hydrodynamics simulation of an evolving and later collapsing pre-stellar core. Using a three-dimensional continuum radiative transfer program, we generate images at 7 micron, 15 micron, 175…

Astrophysics · Physics 2009-11-10 J. Steinacker , B. Lang , A. Burkert , A. Bacmann , Th. Henning

An empirical numerical model that includes nuclear absorption, multiple Coulomb scattering, and energy loss is presented in this work to calculate the transmission of the thick objects in high energy proton radiography, and in this…

Instrumentation and Detectors · Physics 2014-10-16 Zheng Na , Xu Hai-bo

We present the results of a mid-infrared (7 micron) imaging survey of a sample of 24 starless dense cores carried out at an angular resolution of 6 arcsec with the ISOCAM camera aboard the Infrared Space Observatory (ISO). The targeted…

A first core is a first hydrostatic object formed in the course of dynamical contraction of a molecular cloud core. Since the inflow pattern changes drastically before and after the first core formation, it is regarded as a milestone in the…

Astrophysics of Galaxies · Physics 2015-05-27 Kohji Tomisaka , Kengo Tomida

Class 0 objects, which are thought to be the youngest protostars, are identified in terms of NIR or radio emission and/or the presence of molecular outflows. We present combined hydrodynamic and radiative transfer simulations of the…

Astrophysics · Physics 2009-11-11 D. Stamatellos , A. P. Whitworth , S. P. Goodwin

We present a code for generating synthetic SEDs and intensity maps from Smoothed Particle Hydrodynamics simulation snapshots. The code is based on the Lucy (1999) Monte Carlo Radiative Transfer method, i.e. it follows discrete luminosity…

Instrumentation and Methods for Astrophysics · Physics 2016-08-03 O. Lomax , A. P. Whitworth

We present a detailed model for the thermal balance, chemistry, and radiative transfer within quiescent dense molecular cloud cores that contain a central protostar. Large variations in the gas temperature are expected to affect the…

Astrophysics · Physics 2009-10-30 S. D. Doty , D. A. Neufeld

We demonstrate the use of the 3D Monte Carlo radiative transfer code PHAETHON to model infrared-dark clouds (IRDCs) that are externally illuminated by the interstellar radiation field (ISRF). These clouds are believed to be the earliest…

Astrophysics of Galaxies · Physics 2015-05-19 D. Stamatellos , M. Griffin , J. Kirk , S. Molinari , B. Sibthorpe , D. Ward-Thompson , A. Whitworth , L. Wilcock

By using Monte Carlo simulation on a ferromagnetic core/antiferromagnetic shell nanoparticle, we investigate in details the exchange bias of the magnetic hysteresis as a function of both core radius and shell thickness, at low temperature.…

Materials Science · Physics 2007-05-23 M. H. Wu , Q. C. Li , J. M. Liu

Remote sensing instruments observe radiation being scattered and absorbed by molecules, aerosol particles, cloud droplets and ice crystals. In order to interpret and accurately model such observations, the vector radiative transfer equation…

Earth and Planetary Astrophysics · Physics 2019-01-08 C. Emde , B. Mayer

We investigate the uncertainties affecting the temperature profiles of dense cores of interstellar clouds. In regions shielded from external ultraviolet radiation, the problem is reduced to the balance between cosmic ray heating, line…

Astrophysics of Galaxies · Physics 2015-05-30 M. Juvela , N. Ysard

The densest infrared dark clouds (IRDCs) may represent the earliest observable stage of high-mass star formation. These clouds are very cold, hence they emit mainly at far-infrared and sub-mm wavelengths. For the first time, Herschel has…

Sub-millimetre dust emission is often used to derive the column density N of dense interstellar clouds. The observations consist of data at several wavelengths but of variable resolution. We examine two procedures that been proposed for the…

Astrophysics of Galaxies · Physics 2015-06-15 M. Juvela , J. Malinen , T. Lunttila