2023/09/01 by Yoshiaki Sofue · 7 citations
Mathematics · Physics and Astronomy · #Astrophysics #Astrophysics and Star Formation Studies #Circular motion #Classical mechanics #Degeneracy (biology) #Galactic plane #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy rotation curve #Geometry #Halo #Kinematics #Mathematics #Milky Way #Physics #Proper motion #Radial velocity #Ring (chemistry) #Rotation (mathematics) #Spiral galaxy #Stars #Stellar, planetary, and galactic studies #Tangent
paper · pdf · doi:10.1007/s10509-023-04231-0
published in Astrophysics and Space Science 368(9) (Springer Science+Business Media)
openalex publication_date 2023/09/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Abstract We analyze the longitude-velocity diagram (LVD) of 12 CO-line emission from archival data and use the most accurate rotation curve (RC) of the Milky Way to transform radial velocity to face-on position in the galactic plane. We point out that the face-on transformation is highly sensitive to the adopted RC, especially in the inner Milky Way, in the sense that deviations of the RC from the true rotation velocity lead either to an artifact hole or overcrowded concentration along the tangent circle for over- or under-estimated RC, respectively. Even if the RC is sufficiently accurate, non-circular motion such as with the 3 kpc expanding ring introduces significant artifacts in the resulting face-on-map, as long as a circular rotation is assumed. On the other hand, if we properly take into account the non-circular motion, it can be used to solve the near-far degeneracy problem of determination of kinematic distance. We thus propose a new method to solve the degeneracy by incorporating the expanding motion of a ring or arms. We apply the method to the LVD of the 3-kpc expanding ring and present its face-on map projected onto the galactic plane for the first time.