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The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. I. Identifying and Characterizing the Protostellar Content of the OMC-2 FIR4 and OMC-2 FIR3 Regions

Tobin, John J. and Furlan, Elise (2019) The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. I. Identifying and Characterizing the Protostellar Content of the OMC-2 FIR4 and OMC-2 FIR3 Regions. Astrophysical Journal, 886 (1). Art. No. 6. ISSN 1538-4357.

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We present Atacama Large Millimeter/submillimeter Array (0.87 mm) and Very Large Array (9 mm) observations toward OMC-2 FIR4 and OMC-2 FIR3 within the Orion integral-shaped filament, thought to be two of the nearest regions of intermediate-mass star formation. We characterize the continuum sources within these regions on ~40 au (0."1) scales and associated molecular line emission at a factor of ~30 better resolution than previous observations at similar wavelengths. We identify six compact continuum sources within OMC-2 FIR4, four in OMC-2 FIR3, and one additional source just outside OMC-2 FIR4. This continuum emission is tracing the inner envelope and/or disk emission on less than 100 au scales. HOPS-108 is the only protostar in OMC-2 FIR4 that exhibits emission from high-excitation transitions of complex organic molecules (e.g., methanol and other lines) coincident with the continuum emission. HOPS-370 in OMC-2 FIR3, with L ~ 360 L⊙, also exhibits emission from high-excitation methanol and other lines. The methanol emission toward these two protostars is indicative of temperatures high enough to thermally evaporate it from icy dust grains; overall, these protostars have characteristics similar to hot corinos. We do not identify a clear outflow from HOPS-108 in ¹²CO, but we find evidence of interaction between the outflow/jet from HOPS-370 and the OMC-2 FIR4 region. A multitude of observational constraints indicate that HOPS-108 is likely a low- to intermediate-mass protostar in its main mass accretion phase and is the most luminous protostar in OMC-2 FIR4. The high-resolution data presented here are essential for disentangling the embedded protostars from their surrounding dusty environments and characterizing them.

Item Type:Article
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URLURL TypeDescription Paper
Tobin, John J.0000-0002-6195-0152
Furlan, Elise0000-0001-9800-6248
Additional Information:© 2019 The American Astronomical Society. Received 2019 July 16; revised 2019 September 17; accepted 2019 September 29; published 2019 November 13. We thank the anonymous referee for useful feedback that improved the quality of the manuscript and acknowledge useful discussions of this work with F. van der Tak, P. Schilke, and H. Beuther. We are grateful for the support from L. Maud at the Dutch Allegro ALMA Regional Center Node for his efforts in reducing the data. J.J.T. acknowledges support from the Homer L. Dodge Endowed Chair, grant 639.041.439 from the Netherlands Organisation for Scientific Research (NWO), and from the National Science Foundation AST-1814762. Z.-Y.L. is supported in part by NASA 80NSSC18K1095 and NSF AST-1716259. S.O. acknowledges support from NSF AAG grant AST-1510021. G.A., M.O., and A.K.D.-R. acknowledge financial support from the State Agency for Research of the Spanish MCIU through the AYA2017-84390-C2-1-R grant (co-funded by FEDER) and through the "Center of Excellence Severo Ochoa" award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709). A.S. gratefully acknowledges funding through Fondecyt regular (project code 1180350) and Chilean Centro de Excelencia en Astrofísica y Tecnologías Afines (CATA) BASAL grant AFB-170002. Astrochemistry in Leiden is supported by the Netherlands Research School for Astronomy (NOVA), by a Royal Netherlands Academy of Arts and Sciences (KNAW) professor prize, and by the European Union A-ERC grant 291141 CHEMPLAN. M.L.R.H. acknowledges support from a Huygens fellowship from Leiden University. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2015.1.00041.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This research made use of APLpy, an open-source plotting package for Python hosted at This research made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2018) Facilities: ALMA - Atacama Large Millimeter Array, VLA - Very Large Array, Spitzer - Spitzer Space Telescope satellite, Herschel - European Space Agency's Herschel space observatory, Mayall - Kitt Peak National Observatory's 4 meter Mayall Telescope. Software: Astropy (; Astropy Collaboration et al. 2018; Greenfield et al. 2013), APLpy (; Robitaille & Bressert 2012), scipy (; Jones et al. 2001), CASA (; McMullin et al. 2007).
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)639.041.439
Ministerio de Economía, Industria y Competitividad (MINECO) AYA2017-84390-C2-1-R
Fondo Europeo de Desarrollo Regional (FEDER)UNSPECIFIED
Severo OchoaSEV-2017-0709
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1180350
Chilean Centro de Excelencia en Astrofísica y Tecnologías Afines (CATA)UNSPECIFIED
Nederlandse Onderzoekschool Voor Astronomie (NOVA)UNSPECIFIED
Royal Netherlands Academy of Arts and SciencesUNSPECIFIED
European Research Council (ERC)291141
Leiden UniversityUNSPECIFIED
Subject Keywords:Star-forming regions; Protostars; Interstellar medium; Star formation; Young stellar objects; Radio interferometry
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Star-forming regions (1565); Protostars (1302); Interstellar medium (847); Star formation (1569); Young stellar objects (1834); Radio interferometry (1346)
Record Number:CaltechAUTHORS:20191114-095233925
Persistent URL:
Official Citation:John J. Tobin et al 2019 ApJ 886 6
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99829
Deposited By: Tony Diaz
Deposited On:14 Nov 2019 18:08
Last Modified:14 Nov 2019 18:08

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