Volume 518, July-August 2010
Herschel: the first science highlights
|Number of page(s)||5|
|Published online||16 July 2010|
Letter to the Editor
Dust, Ice, and Gas In Time (DIGIT) Herschel program first results*
A full PACS-SED scan of the gas line emission in protostar DK Chamaeleontis
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 78,
Cambridge, MA 02138, USA e-mail: firstname.lastname@example.org
2 The University of Texas at Austin, Department of Astronomy, 1 University Station C1400, Austin, Texas 78712-0259, USA
3 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
4 Max-Planck-Institut für extraterrestriche Physik. Garching, Germany
5 Herschel Science Centre, European Space Astronomy Centre (ESA), PO Box 78, 28691 Villanueva de la Cañada (Madrid), Spain
6 Department of Astronomy and Space Science, Astrophysical Research Center for the Structure and Evolution of the Cosmos, Sejong University, Seoul 143-747, Republic of Korea
7 Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen K., Denmark
8 Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
9 Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
10 (Postdoctoral Fellow of the Fund for Scientific Research, Flanders, Belgium)
11 Astronomy Department, University of California, Berkeley, CA 94720, USA
12 Laboratoire d'Astrophysique de Grenoble, CNRS/Université Joseph Fourier (UMR5571) BP 53, 38041 Grenoble Cedex 9, France
13 Department of Astronomy, The University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042, USA
14 Caltech, Division of Geological & Planetary Sciences, Mail Code 150-21, Pasadena, CA 91125
15 Naval Research Laboratory, Code 7211, Washington, DC 20375, USA
16 Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822, USA ; Spitzer Fellow
17 Astronomical Institute “Anton Pannekoek”, University of Amsterdam, PO Box 94249, 1090 GE Amsterdam, The Netherlands
18 Department of Astrophysics/IMAPP, Radboud University Nijmegen, PO Box 9010 6500 GL Nijmegen, The Netherlands
19 Institut für Theoretische Astrophysik, Universitt Heidelberg, Albert-Ueberle-Strasse 2, 69120 Heidelberg, Germany
20 University of Vienna, Department of Astronomy, Türkenschanzstr. 17, 1180 Vienna, Austria
21 Department of Astronomy, University of Maryland, College Park, MD 20742, USA
22 Dpt. de Física Teórica, Fac. de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
23 SRON Netherlands Institute for Space Research, PO Box 800, 9700 AV, Groningen, The Netherlands
24 National Optical Astronomy Observatory, 950 N. Cherry Ave., Tucson, AZ 85719, USA
Accepted: 14 May 2010
Aims. We aim to study the composition and energetics of the circumstellar material of DK Cha, an intermediate-mass star in transition from an embedded configuration to a star plus disk stage, during this pivotal stage of its evolution.
Methods. Using the range scan mode of PACS on the Herschel Space Observatory, we obtained a spectrum of DK Cha from 55 to 210 μm as part of the DIGIT key program.
Results. Almost 50 molecular and atomic lines were detected, many more than the 7 lines detected in ISO-LWS. Nearly the entire ladder of CO from J = 14–13 to 38–37 (Eu/k = 4080 K), water from levels as excited as = 707 (Eu/k = 843 K), and OH lines up to Eu/k = 290 K were detected.
Conclusions. The continuum emission in our PACS SED scan matches the flux expected by a model consisting of a star, a surrounding disk of 0.03 , and an envelope of a similar mass, supporting the suggestion that the object is emerging from its main accretion stage. Molecular, atomic, and ionic emission lines in the far-infrared reveal the outflow's influence on the envelope. The inferred hot gas may be photon-heated, but some emission may be caused by C-shocks in the walls of the outflow cavity.
Key words: astrochemistry / circumstellar matter / stars: formation / stars: protostars / infrared: ISM / submillimeter: ISM
© ESO, 2010
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