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The Herschel Gould Belt Survey in Chamaeleon II - Properties of cold dust in disks around young stellar objects

Spezzi, L. and Cox, N. L. J. and Prusti, T. and Merín, B. and Ribas, Á. and Alves de Oliveira, C. and Winston, E. and Kóspál, Á. and Royer, P. and Vavrek, R. and André, Ph. and Pilbratt, G. L. and Testi, L. and Bressert, E. and Ricci, L. and Men’shchikov, A. and Könyves, V. (2013) The Herschel Gould Belt Survey in Chamaeleon II - Properties of cold dust in disks around young stellar objects. Astronomy and Astrophysics, 555 . Art. No. A71. ISSN 0004-6361.

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Context. We report on the Herschel Gould Belt survey (HGBS) of the Chamaeleon II (Cha II) star-forming region, focusing on the detection of Class I to III young stellar objects (YSOs). Aims. We aim at characterizing the circumstellar material around these YSOs and at understanding which disk parameters are most likely constrained by the new HGBS data, which are expected to be crucial for studying the transition from optically thick disks to evolved debris-type disks. Methods. We recovered 29 of the 63 known YSOs in Cha II with a detection in at least one of the PACS/SPIRE pass-bands: 3 Class I YSOs (i.e.,100%), 1 flat source (i.e., 50%), 21 Class II objects (i.e., 55%), 3 Class III objects (i.e, 16%), and the unclassified far-infrared source IRAS 12522-7640. We explored PACS/SPIRE colors of this sample and modeled their spectral energy distributions (SEDs) from the optical to Herschel’s wavelengths with the RADMC-2D radiative transfer code. Results. We find that YSO colors are typically confined to the following ranges: −0.7 ≲ log (F_(70)/F_(160)) ≲ 0.5, −0.5 ≲ log (F_(160)/F_(250)) ≲ 0.6, 0.05 ≲ log (F_(250)/F_(350)) ≲ 0.25 and −0.1 ≲ log (F_(350)/F_(500)) ≲ 0.5. These color ranges are expected to be only marginally contaminated by extragalactic sources and field stars and, hence, provide a useful YSO selection tool when applied together. We were able to model the SED of 26 of the 29 detected YSOs. We discuss the degeneracy/limitations of our SED fitting results and adopted the Bayesian method to estimate the probability of different values for the derived disk parameters. The Cha II YSOs present typical disk inner radii ≲0.1 AU, as previously estimated in the literature on the basis of Spitzer data. Our probability analysis shows that, thanks to the new Herschel data, the lower limits to the disk mass (M_(disk)) and characteristic radius (R_C) are well constrained, while the flaring angle (1 + φ) is only marginally constrained. The lower limit to R_C is typically around 50 AU. The lower limits to M_(disk) are proportional to the stellar masses with a typical 0.3% ratio, i.e., in the range estimated in the literature for young Class II stars and brown dwarfs across a broad range of stellar masses. The estimated flaring angles, although very uncertain, point toward very flat disks (1 + φ ≲ 1.2), as found for low-mass M-type YSO samples in other star-forming regions. Thus, our results support the idea that disk properties show a dependence on stellar properties.

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Testi, L.0000-0003-1859-3070
Additional Information:© 2013 ESO. Article published by EDP Sciences. Received 11 March 2013. Accepted 17 May 2013. PACS has been developed by a consortium of institutes led by MPE (Germany) and including UVIE (Austria); KU Leuven, CSL, IMEC (Belgium); CEA, LAM (France); MPIA (Germany); INAF/IFSI/OAA/OAP/OAT, LENS, SISSA (Italy); IAC (Spain). This development has been supported by the funding agencies BMVIT (Austria), ESA-PRODEX (Belgium), CEA/CNES (France), DLR (Germany), ASI/INAF (Italy), and CICYT/MCYT (Spain). SPIRE has been developed by a consortium of institutes led by Cardiff University (UK) and including Univ. Lethbridge (Canada); NAOC (China); CEA, LAM (France); IFSI, Univ. Padua (Italy); IAC (Spain); Stockholm Observatory (Sweden); Imperial College London, RAL, UCLMSSL, UKATC, Univ. Sussex (UK); and Caltech, JPL, NHSC, Univ. Colorado (USA). This development has been supported by national funding agencies: CSA (Canada); NAOC (China); CEA, CNES, CNRS (France); ASI (Italy); MCINN (Spain); SNSB (Sweden); STFC (UK); and NASA (USA). We are grateful to Juan M. Alcalá for providing the spectral type estimate of IRAS 12500-7658. We thank Kees Dullemond for the many explanations on typical parameter ranges for disk around T Tauri stars and the use of RADMC, and Daniel Dale, Luca Cortese and Margherita Bonzini for useful discussions on PACS/SPIRE colors of extragalactic sources. We are grateful to an anonymous referee, whose suggestions have helped us to improve the presentation of this work. N.L.J.C. and P.R. acknowledge support from the Belgian Federal Science Policy Office via the PRODEX Programme of ESA. This research has made use of the SIMBAD database, operated at CDS (Strasbourg, France) and data products from the Wide-field Infrared Survey Explorer (WISE), which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration.
Funding AgencyGrant Number
Istituto Nazionale di Astrofisica (INAF)UNSPECIFIED
Agenzia Spaziale Italiana (ASI)UNSPECIFIED
Canadian Space Agency (CSA)UNSPECIFIED
National Astronomical Observatories, Chinese Academy of Sciences (NAOC)UNSPECIFIED
Commissariat à l’Energie Atomique (CEA)UNSPECIFIED
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Agenzia Spaziale Italiana (ASI)UNSPECIFIED
Swedish National Space Board (SNSB)UNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
Belgian Federal Science Policy Office (BELSPO)UNSPECIFIED
Subject Keywords:stars: pre-main sequence, ISM: clouds, infrared: stars, protoplanetary disks, instrumentation: miscellaneous, ISM: individual objects: Chamaeleon II
Record Number:CaltechAUTHORS:20131002-093920338
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Official Citation:The Herschel Gould Belt Survey in Chamaeleon II - Properties of cold dust in disks around young stellar objects L. Spezzi, N. L. J. Cox, T. Prusti, B. Merín, Á. Ribas, C. Alves de Oliveira, E. Winston, Á. Kóspál, P. Royer, R. Vavrek, Ph. André, G. L. Pilbratt, L. Testi, E. Bressert, L. Ricci, A. Men’shchikov and V. Könyves A&A 555 A71 (2013) DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:41603
Deposited By: Ruth Sustaita
Deposited On:02 Oct 2013 17:54
Last Modified:22 Nov 2019 23:35

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