Outer Rotation Curve of the Galaxy with VERA II: Annual Parallax and Proper Motion of the Star-Forming Region IRAS21379+5106

Abstract

We conducted astrometric VLBI observations of water-vapor maser emission in the massive star forming region IRAS 21379+5106 to measure the annual parallax and proper motion, using VERA. The annual parallax was measured to be $0.262\pm 0.031$ mas corresponding to a trigonometric distance of $3.82_{-0.41}^{+0.51}$ kpc. The proper motion was $({\mu }_{\alpha }\cos \delta ,{\mu }_{\delta })=(-2.74\pm 0.08,-2.87\pm 0.18)$ mas yr${}^{-1}$. Using this result, the Galactic rotational velocity was estimated to be $V_{\theta }=218\pm 19$ km s${}^{-1}$ at the Galactocentric distance $R=9.22\pm 0.43$ kpc, when we adopted the Galactic constants $R_0=8.05\pm 0.45$ kpc and $V_0=238\pm 14$ km s${}^{-1}$. With newly determined distance, {the bolometric luminosity of the central young stellar object was re-evaluated to $(2.15\pm 0.54)\times 10^3{L}_{\odot }$, which corresponds to spectral type of} B2--B3. Maser features were found to be distributed along a straight line from south-west to north-east. In addition, a vector map of the internal motions constructed from the residual proper motions implies that maser features trace a bipolar flow and that it cannot be explained by simple ballistic motion.

13 pages, 7 figures, 6 tables

References in corpus (1)

• Trigonometric Parallaxes of Massive Star Forming Regions: VI. Galactic Structure, Fundamental Parameters and Non-Circular Motions

Cited by in corpus (4)

• Rotation and Mass in the Milky Way and Spiral Galaxies
• Constraining the pitch angle of the Galactic spiral arms in the Milky Way
• Vertical Structure and Kinematics of the Galactic Outer Disk
• Rotation Curve of the Milky Way and the Dark Matter Density