Reconstructing the density and temperature structure of prestellar cores from Herschel data: A case study for B68 and L1689B^⋆

¹ Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot, IRFU/Service d’Astrophysique, C.E. Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette, France
e-mail: Arabindo.Roy@cea.fr; philippe.andre@cea.fr
² Institut d’Astrophysique Spatiale, CNRS/Université Paris-Sud 11, 91405 Orsay, France
³ Université de Bordeaux, Laboratoire d’Astrophysique de Bordeaux, CNRS/INSU, UMR 5804, BP 89, 33271 Floirac Cedex, France
⁴ School of Physics & Astronomy, Cardiff University, Cardiff CF29 3AA, UK
⁵ Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE, UK
⁶ INAF-Istituto di Astrofisica e Planetologia Spaziali, via Fosso del Cavaliere 100, 00133 Rome, Italy
⁷ Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura, Santiago, Chile
⁸ Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8, Canada
⁹ Université de Toulouse, UPS-OMP, IRAP, Toulouse, France
¹⁰ CNRS, IRAP, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
¹¹ Institut d’Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98 bis boulevard Arago, 75014 Paris, France
¹² Department of Physics and Astronomy, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
¹³ RAL Space, STFC Rutherford Appleton Laboratory, Chilton Didcot OX11 0QX, UK

Received: 9 July 2013
Accepted: 8 November 2013

Abstract

Utilizing multiwavelength dust emission maps acquired with Herschel, we reconstruct local volume density and dust temperature profiles for the prestellar cores B68 and L1689B using an inverse-Abel transform-based technique. We present intrinsic radial dust temperature profiles of starless cores directly from dust continuum emission maps disentangling the effect of temperature variations along the line of sight, which were previously limited to the radiative transfer calculations. The reconstructed dust temperature profiles show a significant drop in the core center, a flat inner part, and a rising outward trend until the background cloud temperature is reached. The central beam-averaged dust temperatures obtained for B68 and L1689B are 9.3 ± 0.5 K and 9.8 ± 0.5 K, respectively, which are lower than the temperatures of 11.3 K and 11.6 K obtained from direct SED fitting. The best mass estimates derived by integrating the volume density profiles of B68 and L1689B are 1.6 M_⊙ and 11 M_⊙, respectively. Comparing our results for B68 with the near-infrared extinction studies, we find that the dust opacity law adopted by the HGBS project, κ_λ = 0.1 × (λ/300 μm)^-2 cm² g^-1 agrees to within 50% with the dust extinction constraints.