Volume 604, August 2017
|Number of page(s)||10|
|Section||Interstellar and circumstellar matter|
|Published online||03 August 2017|
Probing changes of dust properties along a chain of solar-type prestellar and protostellar cores in Taurus with NIKA⋆,⋆⋆
1 Laboratoire AIM, CEA/IRFU, CNRS/INSU, Université Paris Diderot, CEA-Saclay, 91191 Gif-Sur-Yvette, France
2 Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
3 Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble Alpes, CNRS/IN2P3, 53 avenue des Martyrs, 38026 Grenoble, France
4 Laboratoire Lagrange, Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Bd de l’Observatoire, CS 34229, 06304 Nice Cedex 4, France
5 Institut de RadioAstronomie Millimétrique (IRAM), 38406 Grenoble, France
6 Astronomy Instrumentation Group, University of Cardiff, Cardiff CF10 3XQ, UK
7 Institut d’Astrophysique Spatiale (IAS), CNRS and Université Paris Sud, 91405 Orsay, France
8 Institut Néel, CNRS and Université Grenoble Alpes, 38042 Grenoble, France
9 Institut de RadioAstronomie Millimétrique (IRAM), 18012 Granada, Spain
10 Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 5, 00185 Roma, Italy
11 Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
12 Aix-Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
13 School of Earth and Space Exploration and Department of Physics, Arizona State University, Tempe, AZ 85287, USA
Received: 5 May 2017
Accepted: 23 June 2017
The characterization of dust properties in the interstellar medium is key for understanding the physics and chemistry of star formation. Mass estimates are crucial to determine gravitational collapse conditions for the birth of new stellar objects in molecular clouds. However, most of these estimates rely on dust models that need further observational constraints to capture the relevant parameter variations depending on the local environment: from clouds to prestellar and protostellar cores. We present results of a new study of dust emissivity changes based on millimeter continuum data obtained with the NIKA camera at the IRAM-30 m telescope. Observing dust emission at 1.15 mm and 2 mm allows us to constrain the dust emissivity index, β, in the Rayleigh-Jeans tail of the dust spectral energy distribution far from its peak emission, where the contribution of other parameters (i.e. dust temperature) is more important. Focusing on the Taurus molecular cloud, one of the most famous low-mass star-forming regions in the Gould Belt, we analyze the emission properties of several distinct objects in the B213 filament. This subparsec-sized region is of particular interest since it is characterized by a collection ofevolutionary stages of early star formation: three prestellar cores, two Class 0/I protostellar cores and one Class II object. We are therefore able to compare dust properties among a sequence of sources that likely derive from the same parent filament. By means of the ratio of the two NIKA channel maps, we show that in the Rayleigh-Jeans approximation, βRJ varies among the objects: it decreases from prestellar cores (βRJ ~ 2) to protostellar cores (βRJ ~ 1) and the Class II object (βRJ ~ 0). For one prestellar and two protostellar cores, we produce a robust study using available Herschel data to constrain the dust temperature of the sources. By using the Abel transform inversion technique we derive accurate radial temperature profiles that allow us to obtain radial β profiles. We find systematic spatial variations of β in the protostellar cores that are not observed in the prestellar core. While in the former case β decreases toward the center (with β varying between 1 and 2), in the latter it remains constant (β = 2.4 ± 0.3). Moreover, the dust emissivity index appears anticorrelated with the dust temperature. We discuss the implication of these results in terms of dust grain evolution between pre- and protostellar cores.
Key words: dust, extinction / ISM: structure / stars: protostars / stars: formation / ISM: individual objects: B213 in Taurus
Based on observations carried out under project number 146-13 with the IRAM 30 m Telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).
The FITS file of the published maps is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/604/A52
© ESO, 2017
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