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Paper: SiO Maser Observations toward Orion-KL with VERA
Volume: 402, Approaching Micro-Arcsecond Resolution with VSOP-2: Astrophysics and Technologies
Page: 469
Authors: Kim, M.K.; Hirota, T.; Honma, M.; Kobayashi, H.; other VERA members
Abstract: We present results of phase-referencing VLBI observations of SiO masers in the Orion KL region made with VERA. The goal of our study is to investigate the dynamics of the gas surrounding Source I, as well as to determine the distance to Orion-KL. We imaged SiO v=1, J=1-0 and v=2, J=1-0 maser emission in Orion-KL and compared the absolute positions of the maser spots with that of Source I. The maser emission shows an X-shaped distribution centered at Source I, and the SiO v=2 emission lies closer to Source I than the SiO v=1 emission. The radial velocities and proper motions of the maser spots indicate that the gas around Source I is rotating and expanding. In addition, we present the preliminary result of the measurement of the annual parallax using the SiO v=2 emission. The parallax of Orion-KL is 2.39±0.03 mas, corresponding to the distance of 418±6 pc.
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