A Herschel and APEX Census of the Reddest Sources in Orion: Searching for the Youngest Protostars
Abstract
We perform a census of the reddest, and potentially youngest, protostars in the Orion molecular clouds using data obtained with the PACS instrument on board the Herschel Space Observatory and the LABOCA and SABOCA instruments on APEX as part of the Herschel Orion Protostar Survey (HOPS). A total of 55 new protostar candidates are detected at 70 μm and 160 μm that are either too faint (m_(24) > 7 mag) to be reliably classified as protostars or undetected in the Spitzer/MIPS 24 μm band. We find that the 11 reddest protostar candidates with log λF_λ70/λF_λ24 > 1.65 are free of contamination and can thus be reliably explained as protostars. The remaining 44 sources have less extreme 70/24 colors, fainter 70 μm fluxes, and higher levels of contamination. Taking the previously known sample of Spitzer protostars and the new sample together, we find 18 sources that have log λF_λ70/λF_λ24 > 1.65; we name these sources "PACS Bright Red sources," or PBRs. Our analysis reveals that the PBR sample is composed of Class 0 like sources characterized by very red spectral energy distributions (SEDs; T_(bol) < 45 K) and large values of sub-millimeter fluxes (L_(smm)/L_(bol) > 0.6%). Modified blackbody fits to the SEDs provide lower limits to the envelope masses of 0.2-2 M_☉ and luminosities of 0.7-10 L_☉. Based on these properties, and a comparison of the SEDs with radiative transfer models of protostars, we conclude that the PBRs are most likely extreme Class 0 objects distinguished by higher than typical envelope densities and hence, high mass infall rates.
Additional Information
© 2013 American Astronomical Society. Received 2012 December 3; accepted 2013 January 26; published 2013 March 22. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. The authors gratefully acknowledge help from Hélène Roussel in the production of Scanamorphos PACS maps. Furthermore, we are grateful to Oskari Miettinen for sharing the reduced SABOCA map of the 090003 region and to Joel Green for providing the SED VLA1623-243. A.M.S. kindly acknowledges helpful and insightful discussions with Ralf Launhardt. The work of A.M.S. was supported by the Deutsche Forschungsgemeinschaft priority program 1573 ("Physics of the Interstellar Medium"). J.T. acknowledges support provided by NASA through Hubble Fellowship grant #HST-HF-51300.01-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This publication is based on data acquired with the Atacama Pathfinder Experiment (APEX). APEX is a collaboration between the Max-Planck-Institut für Radioastronomie, the European Southern Observatory, and the Onsala Space Observatory. The Herschel spacecraft was designed, built, tested, and launched under a contract to ESA managed by the Herschel/Planck Project team by an industrial consortium under the overall responsibility of the prime contractor Thales Alenia Space (Cannes), and including Astrium (Friedrichshafen), responsible for the payload module and for system testing at spacecraft level; Thales Alenia Space (Turin), responsible for the service module; and Astrium (Toulouse), responsible for the telescope, with in excess of a hundred subcontractors. 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). HCSS/HSpot/HIPE is a joint development (are joint developments) by the Herschel Science Ground Segment Consortium, consisting of ESA, the NASA Herschel Science Center, and the HIFI, PACS, and SPIRE consortia. We also use the Spitzer Space Telescope and the Infrared Processing and Analysis Center (IPAC) Infrared Science Archive, which are operated by JPL/Caltech under a contract with NASA. This research has made use of the SIMBAD database and VizieR catalog access tool, operated at CDS, Strasbourg, France. Support for this work was provided by the National Aeronautics and Space Administration (NASA) through awards issued by the Jet Propulsion Laboratory, California Institute of Technology (JPL/Caltech).Attached Files
Published - 0004-637X_767_1_36.pdf
Submitted - 1302.1203v1.pdf
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Additional details
- Eprint ID
- 38264
- Resolver ID
- CaltechAUTHORS:20130503-114340873
- 1573
- Deutsche Forschungsgemeinschaft (DFG)
- HF-51300.01-A
- NASA Hubble Fellowship
- NAS 5-26555
- NASA
- Space Telescope Science Institute
- NSF
- Bundesministerium für Verkehr, Innovation und Technologie (BMVIT)
- ESA-PRODEX (Belgium)
- Centre National de la Recherche Scientifique (CNRS)
- Deutsches Zentrum für Luft- und Raumfahrt (DLR)
- Agenzia Spaziale Italiana (ASI)
- Comisión Interministerial de Ciencia y Tecnología (CICYT)
- NASA/JPL/Caltech
- European Space Agency (ESA)
- NASA Herschel Science Center
- HIFI
- PACS
- SPIRE Consortia
- Istituto Nazionale di Astrofisica (INAF)
- Centre National d'Études Spatiales (CNES)
- Ministerio de Ciencia Y Tecnologia (MCYT)
- Created
-
2013-05-03Created from EPrint's datestamp field
- Updated
-
2021-11-09Created from EPrint's last_modified field
- Caltech groups
- Infrared Processing and Analysis Center (IPAC)