2015/03/25 by Hiroyuki Nakanishi, Nobuyuki Sakai, Tomoharu Kurayama +8
Physics and Astronomy · #Astrometry #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Galaxy rotation curve #Luminosity #Maser #Parallax #Physics #Proper motion #Stars #Stellar, planetary, and galactic studies #Very-long-baseline interferometry #astro-ph.GA
paper · pdf · doi:10.1093/pasj/psv012
13 pages, 7 figures, 6 tables
arxiv created 2015/03/25 · openalex publication_date 2015/03/29 · arxiv updated 2015/06/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract We conducted astrometric very long baseline interferometry (VLBI) observations of water-vapor maser emission in the massive star-forming region IRAS 21379+5106 in order to measure the annual parallax and proper motion, using VLBI Exploration of Radio Astrometry (VERA). The annual parallax measured 0.262 ± 0.031 mas, corresponding to a distance of 3.82+0.51-0.41 kpc. The proper motion was (μαcos δ, μδ) = (−2.74 ± 0.08, −2.87 ± 0.18) mas yr−1. By using this result, the Galactic rotational velocity was estimated to be Vθ = 218 ± 19 km s−1 at the galactocentric distance R = 9.22 ± 0.43 kpc, when we adopted the Galactic constants R0 = 8.05 ± 0.45 kpc and V0 = 238 ± 14 km s−1. With the newly determined distance, the bolometric luminosity of the central young stellar object was reestimated to be (2.15 ± 0.54) × 103 L⊙, which corresponds to the spectral type of B2–B3. The maser features were found to be distributed along a straight line extending from the southwest to the northeast. In addition, a vector map of the internal motions, constructed from the residual proper motions, implies that the maser features trace a bipolar flow, and that it cannot be explained by simple ballistic motions.