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

November 2019 • 2019ApJ...886....6T

Authors • Tobin, John J. • Megeath, S. Thomas • van't Hoff, Merel • Díaz-Rodríguez, Ana Karla • Reynolds, Nickalas • Osorio, Mayra • Anglada, Guillem • Furlan, Elise • Karnath, Nicole • Offner, Stella S. R. • Sheehan, Patrick D. • Sadavoy, Sarah I. • Stutz, Amelia M. • Fischer, William J. • Kama, Mihkel • Persson, Magnus • Di Francesco, James • Looney, Leslie W. • Watson, Dan M. • Li, Zhi-Yun • Stephens, Ian • Chandler, Claire J. • Cox, Erin • Dunham, Michael M. • Kratter, Kaitlin • Kounkel, Marina • Mazur, Brian • Murillo, Nadia M. • Patel, Lisa • Perez, Laura • Segura-Cox, Dominique • Sharma, Rajeeb • Tychoniec, Łukasz • Wyrowski, Friedrich

Abstract • 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.

Links

• PREPRINT http://arxiv.org/abs/1910.00605
• ELECTR https://doi.org/10.3847/1538-4357/ab498f
• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2019ApJ...886....6T
• PDF https://iopscience.iop.org/article/10.3847/1538-4357/ab498f/pdf
• DATA https://irsa.ipac.caltech.edu/bibdata/2019/T/2019ApJ...886....6T.html
• DATA http://archive.eso.org/bin/ads2eso?2019ApJ...886....6T
• DATA http://archive.eso.org/bin/ads2eso?2019ApJ...886....6T