Outer rotation curve of the Galaxy with VERA. IV. Astrometry of IRAS 01123+6430 and the possibility of cloud–cloud collision. (24th October 2019)

• Record Type: Journal Article
• Authors: Koide, Nagito; Nakanishi, Hiroyuki; Sakai, Nobuyuki; Habe, Asao; Shima, Kazuhiro; Kurayama, Tomoharu; Matsuo, Mitsuhiro; Tezuka, Daisuke; Kurahara, Kohei; Ueno, Saeko; Burns, Ross A; Nakagawa, Akiharu; Honma, Mareki; Shibata, Katsunori M; Nagayama, Takumi; Kawaguchi, Noriyuki
• Is Part Of: Publications of the Astronomical Society of Japan. Volume 71:Number 6(2019:Dec.)
• Publication Date: 2019-10-24
• Subjects: ISM: clouds -- ISM: individual objects (IRAS 01123+6430) -- parallaxes -- radio lines: ISM -- stars: formation; Astronomy -- Periodicals; 520.5
• DOI: 10.1093/pasj/psz101
• Languages: English
• ISSNs: 0004-6264

Abstract

Abstract: As part our investigation into the Galactic rotation curve, we carried out Very Long Baseline Interferometry (VLBI) observations towards the star-forming region IRAS 01123+6430 using VLBI Exploration of Radio Astrometry (VERA) to measure its annual parallax and proper motion. The annual parallax was measured to be 0.151 ± 0.042 mas, which corresponds to a distance of $D = 6.61^{+2.55}_{-1.44}\:{\rm kpc}$, and the obtained proper motion components were $(\mu _\alpha {\rm cos}\delta, \, \mu _\delta ) = (-1.44 \pm 0.15, \, -0.27 \pm 0.16)\:{\rm mas\:yr^{-1}}$ in equatorial coordinates. Assuming Galactic constants of $(R_0, \, \Theta _0) = (8.05 \pm 0.45\:{\rm kpc}, \, 238 \pm 14\:{\rm km\:s^{-1}})$, the Galactocentric distance and rotation velocity were measured to be $(R, \, \Theta ) = (13.04 \pm 2.24\:{\rm kpc}, \, 239 \pm 22\:{\rm km\:s^{-1}})$, which are consistent with a flat Galactic rotation curve. The newly estimated distance provides a more accurate bolometric luminosity of the central young stellar object, $L_{\rm Bol} = (3.11 \pm 2.86) \times 10^{3}\, L_{\odot }$, which corresponds to a spectral type of B1–B2. Analysis of ${}^{12}{\rm{CO}}$ ( J = 1–0) survey data obtained with the Five College Radio Astronomical Observatory (FCRAO) 14 m telescope shows that the molecular cloud associated with IRAS 01123+6430 consists of arc-like and linear components, which matches well a structure predicted by numerical simulation of the cloud–cloud collision phenomenon. The coexistence of arc-like and linear components implies that the relative velocity of the two initial clouds was as slow as 3–$5\:{\rm km\, s^{-1}}$, which meets the expected criteria of massive star formation where the core mass is effectively increased in the presence of low relative velocity (∼3–5 km s −1 ), as suggested by Takahira, Tasker, and Habe (2014, ApJ, 792, 63).