Accretion, Infall and a Mysterious One Sided Molecular Jet: SOFIA Observations of Intermediate Mass Protostars in Orion
Abstract
Observations of intermediate luminosity protostars promise new insights into mass accretion, the role of episodic accretion in low mass star formation, and the impact of feedback from protostars on the surrounding cloud. The Herschel Orion Protostar Survey found that ~10% of Orion protostars have intermediate luminosities between 20-1000 solar luminosities. We present SOFIA imaging and spectroscopy with FORCAST of five intermediate luminosity protostars in the Orion molecular clouds and GREAT spectroscopy of an outflow driven by one of the five. FORCAST 9-14 micron spectra and 19.7 and 22.7 micron images are combined with data from HOPS to constrain the luminosities and envelope properties of the protostars; in this contribution we concentrate on the properties of the protostar OMC2-FIR3 (or HOPS 370). This protostars is driving a powerful outflow previously mapped by Herschel/PACS in the 63 micron [OI] line. GREAT [OI] and CO 16-15 spectra combined with an APEX CO 6-5 map resolve the kinematics of this outflow. They show, contrary to prior expectation, that the far-IR lines from the southern lobe are dominated by emission from the swept up gas and that there is no detected far-IR, high velocity jet. In contrast, for the northern lobe of the outflow, a high velocity jet is detected in the CO and [OI] lines. We propose that UV radiation from the terminal shock of the southern lobe, which is propagating into a high density structure, is heating the gas entrained by the outflow and dissociating/ionizing the southern jet. In contrast, the northern jet, which is propagating into lower density gas, and where the terminal shock is much further from the driving protostar, is not exposed to a strong UV field. We also assess the potential UV contribution from a nearby luminous companion to OMC2-FIR3. These observations suggest that differences in the ambient cloud density can alter the properties of outflows and the atomic and molecular lines used to trace them. Financial support for this work was provided by NASA through awards SOF3-0097 and SOF4-0090 and issued by USRA.
- Publication:
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American Astronomical Society Meeting Abstracts #233
- Pub Date:
- January 2019
- Bibcode:
- 2019AAS...23332006M