Using VLBI to Probe the Orion-KL Outflow on AU Scales

Abstract

We present the first contemporaneous 43GHz and 86GHz VLBI images of the v=1 J=2-1 and J=1-0 SiO masers in the Orion-KL nebula. Both maser species exhibit the same general morphology of earlier J=1-0 maser images which appear to trace the edges of a bi-polar conical outflow. Surprisingly, the J=2-1 masers form further from the central protostar than the J=1-0 masers, a fact not readily explained by current SiO maser pumping models. The average magnitude of offsets between corresponding regions of the two masing transitions is approximately 14% of the total radial extent of the SiO maser emission. This offset indicates that each transition must trace different physical conditions.

arXiv comment20 pages, 4 figures

References in corpus (3)

• Coexisting conical bipolar and equatorial outflows from a high-mass protostar
• Numerical simulations of stellar SiO maser variability. Investigation of the effect of shocks
• Outflow 20--2000 AU from a High-Mass Protostar in W51-IRS2

Cited by in corpus (8)

• A Feature Movie of SiO Emission 20-100 AU from the Massive Young Stellar Object Orion Source I
• A line confusion limited millimeter survey of Orion KL. II: Silicon-bearing species
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• Maser emission from SiO isotopologues traces the innermost 100 AU around Radio Source I in Orion BN/KL
• VLBA imaging of the 3mm SiO maser emission in the disk-wind from the massive protostellar system Orion Source I
• First VLBI mapping of circumstellar 29SiO maser emission
• ALMA Observation of the 658 GHz Vibrationally Excited H${}_2$O Maser in Orion KL Source I
• Masers and star formation