Outer rotation curve of the Galaxy with VERA. II. Annual parallax and proper motion of the star-forming region IRAS 21379+5106

• DOI: 10.1093/pasj/psv012
• Publication Date: 2015-03-29T03:47:40Z
• Authors: Hiroyuki Nakanishi; Nobuyuki Sakai; Tomoharu Kurayama; Mitsuhiro Matsuo; Hiroshi Imai; Ross A. Burns; Takeaki Ozawa; Mareki Honma; Katsunori M. Shibata; Noriyuki Kawaguchi
• Keywords: Parallax; Astrometry; Very-long-baseline interferometry; Proper motion

We conducted astrometric VLBI observations of water-vapor maser emission in the massive star forming region IRAS 21379+5106 to measure annual parallax and proper motion, using VERA. The was measured be $0.262 \pm 0.031$ mas corresponding a trigonometric distance $3.82^{+0.51}_{-0.41}$ kpc. motion $(\mu_\alpha\cos{\delta}, \mu_\delta)=(-2.74 0.08, -2.87 0.18)$ yr$^{-1}$. Using this result, Galactic rotational velocity estimated $V_\theta=218\pm 19$ km s$^{-1}$ at Galactocentric $R=9.22\pm0.43$ kpc, when we adopted constants $R_0=8.05\pm 0.45$ kpc $V_0=238\pm 14$ s$^{-1}$. With newly determined distance, {the bolometric luminosity central young stellar object re-evaluated $(2.15\pm 0.54)\times 10^3 L_\odot$, which corresponds spectral type of} B2--B3. Maser features were found distributed along straight line from south-west north-east. In addition, vector map internal motions constructed residual implies that trace bipolar flow it cannot explained by simple ballistic motion.