What does the Milky Way look like? (2023)
Keywords :
Galaxy structure ; Milky Way Galaxy ; Trigonometric parallax
Abstract:In spite of much work, the overall spiral structure morphology of the Milky Way remains somewhat uncertain. In the last two decades, accurate distance measurements have provided us with an opportunity to solve this issue. Using the precise locations of very young objects, for the first time, we propose that our galaxy has a multiple-arm morphology that consists of two-arm symmetry (the Perseus and Norma Arms) in the inner parts and that extends to the outer parts, where there are several long, irregular arms (the Centaurus, Sagittarius, Carina, Outer, and Local Arms).
...(more)
VLBI at radio wavelengths has been used to detect a large amount of
masers associated with high-mass star-forming regions (HMSFRs), and
they can be used to map the spiral structure of the MW from the solar
neighborhood to the Galactic center (GC) and beyond. Table 1 lists the
coordinates and parallaxes of 204 HMSFR masers measured with VLBI
techniques, including the National Radio Astronomy Observatory's Very
Long Baseline Array, the Japanese VLBI Exploration of Radio Astrometry
project, the European VLBI Network, and the Australian Long Baseline
Array. For the masers listed in Table 1, 199 were summarized by R19
(Reid+ 2019, J/ApJ/885/131), and five have been newly reported by
Xu+ 2021ApJS..253....1X and Bian+ 2022AJ....163...54B in the past 2yr.
See Section 2.
We obtain a sample of 185 external MW-like galaxies from the the Sloan
Digital Sky Survey (SDSS) DR7 in the g band or Digitized Sky Survey
(DSS) in the blue band. See Appendix B.
- VIII/39 : Composite CO Survey of the Milky Way (Dame+ 1987)
- II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
- J/A+A/397/133 : Star-forming complexes in the Galaxy (Russeil+, 2003)
- J/A+A/569/A125 : Spiral structure of the Milky Way (Hou+, 2014)
- J/ApJ/798/L27 : CO obs. of MoCs in the 2nd quadrant (Sun+, 2015)
- J/ApJS/224/7 : CO obs. of the outer arm in the 2nd quadrant (Du+, 2016)
- J/A+A/594/A116 : HI4PI spectra and column density maps (HI4PI team+, 2016)
- J/A+A/616/A10 : Open clusters GaiaDR2 HR diag. (Gaia Collaboration, 2018)
- J/A+A/616/L15 : Parallaxes and Proper Motions of OB stars (Xu+, 2018)
- J/other/RAA/18.146 : Spiral structure of the Milky Way (Xu+, 2018)
- J/ApJ/885/131 : High-mass SFR plx & proper motion with VLBI (Reid+, 2019)
- J/A+A/652/A102 : 3794 open clusters parameters (Hao+, 2021)
- J/A+A/651/A104 : Spiral arms Gaia EDR3 (Poggio+, 2021)
- J/A+A/645/L8 : Plxs & proper motions of OB stars from Gaia (Xu+, 2021)
- J/A+A/661/A118 : Open clusters found with OCfinder (Castro-Ginard+, 2022)
- J/A+A/660/A4 : Gaia EDR3 new Galactic open clusters (Hao+, 2022)
- http://www.sdss.org/ : SDSS home page