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arXiv · 2509.20551

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

Phillip Oakey·Yao-Lun Yang·Jonathan C. Tan·Thomas G. Bisbas·Rubén Fedriani·Kei Tanaka·Zoie Telkamp·Yichen Zhang·Christian Fischer·Lianis Reyes Rosa
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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\ $^3P_2\rightarrow^3P_1$ emission at 52 \micron\ from the massive protostar G11.94-0.62, tracing highly ionized gas. We also detect \OI\ $^3P_2\rightarrow^3P_1$ and $^3P_1\rightarrow^3P_0$ at 63 and 145 \micron\ tracing atomic gas, as well as CO $J=14\rightarrow13$ at 186 \micron\ from highly excited molecular gas. The \OIII\ and \OI\ lines exhibit large line widths ($\sim200$ and $\sim40-80$ \kms, respectively) and their morphologies are consistent with a wide-angle bipolar outflow. The properties of molecular tracers ($^{12}$CO, $^{13}$CO, C$^{18}$O, H$_2$CO, and CH$_3$OH) observed with ALMA support this interpretation. Ionized nebula and PDR modeling imply an ionized outflow mass flux of $\sim8\times10^{-5}\:M_\odot$ yr$^{-1}$ and an atomic outflow mass flux of $\sim5\times10^{-6}\:M_\odot$ yr$^{-1}$, while the molecular outflow traced by CO has an implied mass flux of $\sim3\times10^{-4}\:M_\odot$ 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.

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Phillip Oakey, Yao-Lun Yang, Jonathan C. Tan, Thomas G. Bisbas, Rubén Fedriani, Kei Tanaka, Zoie Telkamp, Yichen Zhang, Christian Fischer, Lianis Reyes Rosa. 2025-09-24. The SOMA Atomic Outflow Survey. I. An Atomic OI and Highly Ionized OIII Outflow from Massive Protostar G11.94-00.62. https://arxiv.org/abs/2509.20551

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