3D continuum radiative transfer in complex dust configurations

II. 3D structure of the dense molecular cloud core Oph D

¹ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany e-mail: [stein;henning;stickel]@mpia.de
² European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
³ Observatoire de Bordeaux, 2 rue de l'Observatoire, BP 89, 33270 Floirac, France e-mail: bacmann@obs.u-bordeaux1.fr
⁴ Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany e-mail: rklessen@aip.de

Received: 9 September 2004
Accepted: 22 October 2004

Abstract

Constraints on the density and thermal 3D structure of the dense molecular cloud core ρ  Oph D are derived from a detailed 3D radiative transfer modeling. Two ISOCAM images at 7 and 15 μm are fitted simultaneously by representing the dust distribution in the core with a series of 3D Gaussian density profiles. Size, total density and position of the Gaussians are optimized by simulated annealing to obtain a 2D column density map. The projected core density has a complex elongated pattern with two peaks. We propose a new method to calculate an approximate temperature in an externally illuminated complex 3D structure from a mean optical depth. This “”-method is applied to a 1.3 mm map obtained with the IRAM 30m telescope to find the approximate 3D density and temperature distribution of the core ρ  Oph D. The spatial 3D distribution deviates strongly from spherical symmetry. The elongated structure is in general agreement with recent gravo-turbulent collapse calculations for molecular clouds. We discuss possible ambiguities of the background determination procedure, errors of the maps, the accuracy of the -method and the influence of the assumed dust particle sizes and properties.