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

John J. Tobin, S. Thomas Megeath, Merel Van T. Hoff, Ana Karla Díaz-Rodríguez, Nickalas Reynolds, Mayra Osorio, Guillem Anglada, Elise Furlan, Nicole Karnath, Stella S.R. Offner, Patrick D. Sheehan, Sarah I. Sadavoy, Amelia M. Stutz, William J. Fischer, Mihkel Kama, Magnus Persson, James Di Francesco, Leslie W. Looney, Dan M. Watson, Zhi Yun LiIan Stephens, Claire J. Chandler, Erin Cox, Michael M. Dunham, Kaitlin Kratter, Marina Kounkel, Brian Mazur, Nadia M. Murillo, Lisa Patel, Laura Perez, Dominique Segura-Cox, Rajeeb Sharma, Łukasz Tychoniec, Friedrich Wyrowski

Research output: Contribution to journalArticlepeer-review

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 o˙, 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.

Original languageEnglish (US)
Article number6
JournalAstrophysical Journal
Volume886
Issue number1
DOIs
StatePublished - Nov 20 2019

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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