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Title: Trigonometric parallaxes of star forming regions in the Scutum spiral arm

We report measurements of trigonometric parallaxes for six high-mass star-forming regions in the Scutum spiral arm of the Milky Way as part of the BeSSeL Survey. Combining our measurements with 10 previous measurements from the BeSSeL Survey yields a total sample of 16 sources in the Scutum arm with trigonometric parallaxes in the Galactic longitude range from 5° to 32°. Assuming a logarithmic spiral model, we estimate a pitch angle of 19.°8 ± 3.°1 for the Scutum arm, which is larger than pitch angles reported for other spiral arms. The high pitch angle of the arm may be due to the arm's proximity to the Galactic bar. The Scutum arm sources show an average peculiar motion of 4 km s{sup –1} slower than the Galactic rotation and 8 km s{sup –1} toward the Galactic center. While the direction of this non-circular motion has the same sign as determined for sources in other spiral arms, the motion toward the Galactic center is greater for the Scutum arm sources.
Authors:
; ; ; ; ; ;  [1] ; ;  [2]
  1. Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)
  2. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
Publication Date:
OSTI Identifier:
22370596
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 793; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; INCLINATION; MASERS; MASS; MILKY WAY; ROTATION; STARS