The SOMA Atomic Outflow Survey. I. An Atomic OI and Highly Ionized OIII Outflow from Massive Protostar G11.94-00.62

2025/09/24 by Phillip Oakey, Yao-Lun Yang, Oakey, Phillip +16
Engineering · Physics and Astronomy · #Astro and Planetary Science #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #SAS software applications and methods #Solar and Stellar Astrophysics (astro-ph.SR) #Spacecraft and Cryogenic Technologies

paper · doi:10.48550/arxiv.2509.20551

openalex publication_date 2025/09/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31

Abstract

Massive stars regulate galaxy evolution and star formation through their physical and chemical feedback, but their formation remains poorly understood. Accretion-powered outflows provide important diagnostics of massive star formation. We present first results from the SOMA Atomic Outflow Survey, a far-infrared massive star formation survey using the FIFI-LS instrument on SOFIA. We report detection of \OIII ³P₂→³P₁ emission at 52 \micron from the massive protostar G11.94-0.62, tracing highly ionized gas. We also detect \OI ³P₂→³P₁ and ³P₁→³P₀ at 63 and 145 \micron tracing atomic gas, as well as CO J=14→13 at 186 \micron from highly excited molecular gas. The \OIII and \OI lines exhibit large line widths (∼200 and ∼40-80 \kms, respectively) and their morphologies are consistent with a wide-angle bipolar outflow. The properties of molecular tracers (¹²CO, ¹³CO, C¹⁸O, H₂CO, and CH₃OH) observed with ALMA support this interpretation. Ionized nebula and PDR modeling imply an ionized outflow mass flux of ∼8×10^-5 M_\odot yr^-1 and an atomic outflow mass flux of ∼5×10^-6 M_\odot yr^-1, while the molecular outflow traced by CO has an implied mass flux of ∼3×10^-4 M_\odot yr^-1. The mass and momentum flux in the ionized outflow are consistent with the primary disk wind, while the molecular component is mainly swept-up, secondary outflow gas. We also observe G11.94-0.62 with the LBT in the near-infrared, potentially tracing the base of wide-angle outflow cavities. SED modeling implies a protostellar mass m_* = 22.4⁺²¹_-11 M_\odot, while the \OIII emission implies m_*\gtrsim30 M_\odot and that the protostar is in the final stages of its accretion.

Citations

• SOFIA FIFI-LS spectroscopy of DR21 Main: energetics of the spatially-resolved outflow from a high-mass protostar
• ALMAGAL I. The ALMA evolutionary study of high-mass protocluster formation in the Galaxy. Presentation of the survey and early results
• The SOFIA Massive (SOMA) Star Formation Survey. V. Clustered Protostars
• The ALMA-QUARKS Survey: II. the ACA 1.3 mm continuum source catalog and the assembly of dense gas in massive star-forming clumps
• The ALMA-QUARKS survey: -- I. Survey description and data reduction
• Characterization and Absolute Calibration of the Far Infrared Field Integral Line Spectrometer for SOFIA
• CASA, the Common Astronomy Software Applications for Radio Astronomy
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• The Two Micron All Sky Survey (2MASS)

Related

• The ALMA-ATOMS Survey: Exploring Protostellar Outflows in HC₃N
• The ALMA-ATOMS-QUARKS survey: Resolving a chemically rich massive protostellar outflow
• Massive molecular outflows
• The ALMA Survey of 70 μm Dark High-mass Clumps in Early Stages (ASHES). XII. Unanchored Forked Stream in the Propagating Path of a Protostellar Outflow
• Outflow and Accretion in Massive Star Forming Regions