Year: 2026
Type: article
Abstract: We present the Atacama Large Millimeter/submillimeter Array (ALMA) and the NOrthern Extended Millimeter Array (NOEMA) observations of the molecular outflow from the high-mass young stellar object (HMYSO) G24.33+0.14, which has recently undergone an accretion burst. CO (2–1) and SiO (5–4) reveal a bipolar outflow with pronounced asymmetry and multiple shells, indicating episodic mass ejection. CO reaches projected velocities up to ∼150 km s −1 , placing the outflow in the extremely high-velocity (EHV) regime. Position–velocity (PV) diagrams show distinct Hubble-wedge structures, and high-velocity CO knots cluster into two separate wedges, supporting nonsteady, multiepoch ejection. Crucially, CH 3 CN ( J = 12–11, K = 0–4) emission is detected along the outflow axis and spatially coincides with SiO (5–4). Its velocity gradient aligns with the outflow, rather than the disk, and the derived rotational temperatures have a median value of 135 K, which, together with its spatial and kinematic association with SiO, supports a shock-related origin of the CH 3 CN emission. Comparison of burst-phase (ALMA 2019) and postburst (NOEMA 2020) data shows significant intensity variations in CO and CH 3 OH masers, confirming that accretion bursts modify outflow physical conditions on observable timescales. These results support a possible connection between episodic accretion, shock chemistry, and extreme-velocity mass ejection in a massive protostar.
Source: The Astrophysical Journal
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Award: G7201860076
OpenAlex ID: W7221170667