Coexisting conical bipolar and equatorial outflows from a high-mass protostar

Area of Science:

• Astrophysics
• Star Formation
• Orion Molecular Cloud

Background:

• The BN/KL region is a key site for studying massive star formation.
• Obscuring dust and gas hinder detailed observations of star-forming regions.
• Protostars are theorized to accrete from disks and eject bipolar outflows.

Purpose of the Study:

• To investigate the immediate environment of radio source I, a potential massive protostar.
• To test theoretical models of accretion and outflow in massive star formation.
• To characterize the gas dynamics around radio source I using maser emission.

Main Methods:

• High-resolution observations of silicon monoxide (SiO) maser emission.
• High-resolution observations of water maser emission.
• Analysis of gas kinematics within 1,000 AU of radio source I.

Main Results:

• A conical bipolar outflow dominates the region within 60 AU of source I.
• The expected rotating equatorial disk is not observed close to the source.
• A slower, wider outflow is detected near the equatorial plane, extending to 1,000 AU.

Conclusions:

• The immediate environment of source I is dominated by a bipolar outflow, not a disk.
• This finding challenges the standard model of disk-driven accretion for massive protostars.
• Outflow dynamics in massive star formation may be more complex than previously thought.