Trigonometric Parallaxes of High-mass Star-forming Regions: Our View of the Milky Way

By M. J. Reid, K. Menten, A. Brunthaler, X. Zheng, T. Dame, Y. Xu, J. Li, N. Sakai, Y. Wu, K. Immer and 8 more. Astrophysical Journal, 2019

434 citations recorded by the source corpus.

We compile and analyze approximately 200 trigonometric parallaxes and proper motions of molecular masers associated with very young high-mass stars. Most of the measurements come from the BeSSeL Survey using the VLBA and the Japanese VERA project. These measurements strongly suggest that the Milky Way is a four-arm spiral, with some extra arm segments and spurs. Fitting log-periodic spirals to the locations of the masers, allowing for “kinks” in the spirals and using well-established arm tangencies in the fourth Galactic quadrant, allows us to significantly expand our view of the structure of the Milky Way. We present an updated model for its spiral structure and incorporate it into our previously published parallax-based distance-estimation program for sources associated with spiral arms. Modeling the three-dimensional space motions yields estimates of the distance to the Galactic center, , the circular rotation speed at the Sun's position, km s−1, and the nature of the rotation curve. Our data strongly constrain the full circular velocity of the Sun, km s−1, and its angular velocity, km s−1 kpc–1. Transforming the measured space motions to a Galactocentric frame which rotates with the Galaxy, we find non-circular velocity components typically ≲10 km s−1. However, near the Galactic bar and in a portion of the Perseus arm we find significantly larger non-circular motions. Young high-mass stars within 7 kpc of the Galactic center have a scale height of only 19 pc, and thus are well suited to define the Galactic plane. We find that the orientation of the plane is consistent with the IAU-defined plane to within ±0.°1, and that the Sun is offset toward the north Galactic pole by pc. Accounting for this offset places the central supermassive black hole, Sgr A*, in the midplane of the Galaxy. The measured motions perpendicular to the plane of the Galaxy limit precession of the plane to ≲4 km s−1 at the radius of the Sun. Using our improved Galactic parameters, we predict the Hulse–Taylor binary pulsar to be at a distance of 6.54 ± 0.24 kpc, assuming its orbital decay from gravitational radiation follows general relativity.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/300c0930fa159c129743e5390266338d07971dc4

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Citations in the corpus

Painting a portrait of the Galactic disc with its stellar clusters (2020, background): “For this arm, Reid et al. (2019) fitted a significantly different location with a pitch angle of 3◦ and RGC ∼ 11 to 13 kpc in the anticentre direction (compared to 13.8◦ and 13 to 15 kpc in Reid et al. 2014).”
First Sagittarius A* Event Horizon Telescope Results. IV. Variability, Morphology, and Black Hole Mass (2022, methodology): “…in the source and the broad morphological diversity of the GRMHD calibration suite that reflects the a priori unknown inclination of Sgr A*. Combining our θg constraint with an independent distance measurement from Reid et al. (2019), we determine the mass of Sgr A* to be M= ´- +4.0 100.6 1.1 6 Me.”
First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole (2022, positive): “The distance is consistent with maser parallax measurements (Reid et al. 2019).”