A Photoionized Accretion Disk around a Young High-mass Star

Abstract

We present high spatial resolution (52 au) observations of the high-mass young stellar object (HMYSO) G345.4938+01.4677 made using the Atacama Large Millimeter/submillimeter Array. This O-type HMYSO is located at 2.38 kpc and is associated with a luminosity of 1.5 × 10⁵ L_⊙. We detect circumstellar emission from the H38β hydrogen recombination line showing a compact structure rotating perpendicularly to the previously detected radio jet. We interpret this emission as tracing a photoionized accretion disk around the HMYSO. While this disk-like structure seems currently too small to sustain continued accretion, the data present direct observational evidence of how disks can effectively survive the photoionization feedback from young high-mass stars. We also report the detection of a low-mass young stellar object in the vicinity of the HMYSO and suggest that it forms a high-mass and low-mass star binary system.