ASTROMETRY AND SPATIO-KINEMATICS OF H sub(2)O MASERS IN THE MASSIVE STAR-FORMING REGION NGC 6334I(NORTH) WITH VERA

• Published in: The Astrophysical journal Vol. 784; no. 2; pp. 1 - 8
• Main Authors: CHIBUEZE, JAMES O, Omodaka, Toshihiro, Handa, Toshihiro, Imai, Hiroshi, KURAYAMA, TOMOHARU, Nagayama, Takumi, Sunada, Kazuyoshi, Nakano, Makoto, Hirota, Tomoya, HONMA, MAREKI
• Format: Journal Article
• Language: English
• Published: 01.04.2014
• Subjects: Astrometry; Continuums; Luminosity; Masers; Outflow; Parallax; Spirals; Star formation; PN, Arctic, North Pole
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637X/784/2/114

We measured the trigonometric parallax of an H sub(2)O maser source associated with the massive star-forming region NGC 6334I(North), hereafter as NGC 6334I(N), with the VLBI Exploration of Radio Astrometry. The derived annual parallax is 0.789 + or - 0.161 mas, corresponding to a distance of 1.26 super(+0.33) sub(-0.21) kpc. Using the new distance, we recalculated the physical parameters (masses and luminosities) of the dust continuum cores in the region, and the revised parameters are only ~50% of their originally reported values. We also traced 23 relative proper motions of the H sub(2)O masers associated with SMA1 (central millimeter source in the region) between epochs, which exhibit an average amplitude of maser proper motion of ~2.03 mas yr super(-1) (~ 12.22 kms super(-1)), tracing a bipolar outflow. The bipolar outflow structure extends through ~600mas (~720AU), with a dynamical timescale of ~295 yr. Using an expanding flow model, we derived the most plausible dynamical center of the outflow, pointing to SMA1b (1.3 cm and 7 mm continuum source) as the outflow driving source. Based on our results and other existing parallax results, we derive the pitch angles of the Sagittarius arm as 6[degrees].2 + or - 5[degrees].4 along the Galactic longitude range of ~0[degrees].7 - ~40[degrees].1 assuming a perfect logarithmic spiral. We derived the peculiar motion of NGC 6334I(N) to be -4 + or - 1 kms super(-1) toward the Galactic center, 8 + or - 2 kms super(-1) in the direction of the Galactic rotation, and 25 + or - 2kms super(-1) toward the Galactic north pole.