The local spiral structure of the Milky Way
Ye Xu1,*, Mark Reid2, Thomas Dame2, Karl Menten3, Nobuyuki Sakai4, Jingjing Li1,3, Andreas Brunthaler3, Luca Moscadelli5, Bo Zhang6 and Xingwu Zheng7
- Author Affiliations
1Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, China.
2Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA.
3Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany.
4Mizusawa VLBI (Very Long Baseline Interferometry) Observatory, National Astronomical Observatory of Japan, Japan.
5INAF (Istituto Nazionale di Astrofisica)–Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy.
6Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China.
7Nanjing University, Nanjing 210093, China.
↵*Corresponding author. Email: xuye@pmo.ac.cn
Science Advances 28 Sep 2016:
Vol. 2, no. 9, e1600878
Abstract
The nature of the spiral structure of the Milky Way has long been debated. Only in the last decade have astronomers been able to accurately measure distances to a substantial number of high-mass star-forming regions, the classic tracers of spiral structure in galaxies. We report distance measurements at radio wavelengths using the Very Long Baseline Array for eight regions of massive star formation near the Local spiral arm of the Milky Way. Combined with previous measurements, these observations reveal that the Local Arm is larger than previously thought, and both its pitch angle and star formation rate are comparable to those of the Galaxy’s major spiral arms, such as Sagittarius and Perseus. Toward the constellation Cygnus, sources in the Local Arm extend for a great distance along our line of sight and roughly along the solar orbit. Because of this orientation, these sources cluster both on the sky and in velocity to form the complex and long enigmatic Cygnus X region. We also identify a spur that branches between the Local and Sagittarius spiral arms.
Key words Masers high angular resolution astrometry star formation galaxy spiral arm
Copyright © 2016, The Authors
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