TRIGONOMETRIC PARALLAXES OF HIGH MASS STAR FORMING REGIONS: THE STRUCTURE AND KINEMATICS OF THE MILKY WAY

By M. J. Reid, K. Menten, A. Brunthaler, X. Zheng, T. Dame, Ye Xu, Yuanbin Wu, B. Zhang, A. Sanna, M. Sato and 6 more. 2014

862 citations recorded by the source corpus.

Over 100 trigonometric parallaxes and proper motions for masers associated with young, high-mass stars have been measured with the Bar and Spiral Structure Legacy Survey, a Very Long Baseline Array key science project, the European VLBI Network, and the Japanese VLBI Exploration of Radio Astrometry project. These measurements provide strong evidence for the existence of spiral arms in the Milky Way, accurately locating many arm segments and yielding spiral pitch angles ranging from about 7° to 20°. The widths of spiral arms increase with distance from the Galactic center. Fitting axially symmetric models of the Milky Way with the three-dimensional position and velocity information and conservative priors for the solar and average source peculiar motions, we estimate the distance to the Galactic center, R0, to be 8.34 ± 0.16 kpc, a circular rotation speed at the Sun, Θ0, to be 240 ± 8 km s−1, and a rotation curve that is nearly flat (i.e., a slope of −0.2 ± 0.4 km s−1 kpc−1) between Galactocentric radii of ≈5 and 16 kpc. Assuming a “universal” spiral galaxy form for the rotation curve, we estimate the thin disk scale length to be 2.44  ±  0.16 kpc. With this large data set, the parameters R0 and Θ0 are no longer highly correlated and are relatively insensitive to different forms of the rotation curve. If one adopts a theoretically motivated prior that high-mass star forming regions are in nearly circular Galactic orbits, we estimate a global solar motion component in the direction of Galactic rotation, V☉ = 14.6 ± 5.0 km s−1. While Θ0 and V☉ are significantly correlated, the sum of these parameters is well constrained, Θ0 + V☉ = 255.2 ± 5.1 km s−1, as is the angular speed of the Sun in its orbit about the Galactic center, (Θ0 + V☉)/R0 = 30.57 ± 0.43 km s−1 kpc−1. These parameters improve the accuracy of estimates of the accelerations of the Sun and the Hulse–Taylor binary pulsar in their Galactic orbits, significantly reducing the uncertainty in tests of gravitational radiation predicted by general relativity.

Subfields: Astronomy and Astrophysics, Education, Instrumentation

View Paper: https://www.semanticscholar.org/paper/20a46c7becb105c9062f65282557a30d0b2f236d

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1. P. McMillan
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4. A. Helmi
5. I. Minchev
6. R. Genzel
7. Hans-Walter Rix
8. P. Hopkins

Citations in the corpus

• Trigonometric Parallaxes of High-mass Star-forming Regions: Our View of the Milky Way (2019, methodology): “Finally, as discussed in Reid et al. (2014), we expect some outliers in the motion data, owing for example to the effects of super-bubbles that can accelerate gas which later forms the stars with the masers we observe.”
• Molecular gas kinematics within the central 250 pc of the Milky Way (2016, background): “Most dense gas within ∼ 150 pc from the Galactic centre (corresponding to an angular distance of ∼ 1◦ at an assumed distance of 8.3 kpc; Reid et al. 2014) is distributed throughout several coherent gas streams spanning ∼ 200 km s−1 in velocity (with significant substructure also evident).”
• Detection of orbital motions near the last stable circular orbit of the massive black hole SgrA* (2018, background): “The absolute positions of SgrA* is extremely well determined based on a radio reference frame, which is tied to nearby Quasars (accuracy < 1 mas, Reid et al. 2014; Plewa et al. 2015).”
• Star formation rates and efficiencies in the Galactic Centre (2017, background): “This analysis, therefore, has been restricted to the |l| < 1◦ and |b| < 0.5◦ region, as parallax measurements (Reid et al. 2009, 2014) and modelling (Molinari et al. 2011; Kruijssen, Dale & Longmore 2015) have shown that the majority of the dense molecular gas and starforming regions are close to…”
• FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope (FUGIN) I: Project Overview and Initial Results (2017, methodology): “The spiral arms, such as the Sagittarius, Scutum, and Norma arms, can be seen at the positive velocity range in the l− v diagrams as estimated by Reid et al. (2014), respectively.”
• A compendium of distances to molecular clouds in the Star Formation Handbook (2020, neutral): “18+5.51”; Reid et al. 2014), and – the W3 star-forming region (“W3OH”; Reid et al. 2014).”
• HERSCHEL SURVEY OF GALACTIC OH+, H2O+, AND H3O+: PROBING THE MOLECULAR HYDROGEN FRACTION AND COSMIC-RAY IONIZATION RATE (2014, methodology): “The H ii region has a large peculiar motion with respect to the Galaxy’s rotation curve, and is 4.95 kpc away from the Sun as determined by H2O maser observations (Sanna et al. 2014).”
• The influence of Sagittarius and the Large Magellanic Cloud on the stellar disc of the Milky Way Galaxy (2017, background): “2It should be noted that the inferences from the shape of the HI warp are based on kinematic distance estimates that are known to be severely biased by up to a factor of two (Reid et al. 2014). as formulated by Blumenthal et al. (1986).”
• The mass distribution and gravitational potential of the Milky Way (2016, methodology): “This represents an increase by more than a fctor of 4 over the number of HMSFRs with known parallaxes used in Paper I.Reid et al.(2014) used these data to determine the Sun’s position and velocity with aχ2 analysis which used the approximation that the HMSFRs were exactly at the position…”
• The Galaxy in Context: Structural, Kinematic, and Integrated Properties (2016, methodology): “Globally determined values of U (Bovy et al. 2012a, Reid et al. 2014) agree well within errors with the locally determined U = 10 ± 1 km s−1.”
• Made-to-measure models of the Galactic box/peanut bulge: stellar and total mass in the bulge region (2015, background): “According to the latest studies (Chatzopoulos et al. 2015; Reid et al. 2014), we assume a distance to the Galactic Centre (GC) of R0 = 8.3kpc.”
• Mapping the Milky Way with LAMOST– III. Complicated spatial structure in the outer disc (2018, methodology): “We adopt that the Sun is located at R0 = 8.34 kpc (Reid et al. 2014) and Z0 = 0.027 kpc (Chen et al. 2001).”
• A PARALLAX DISTANCE TO THE MICROQUASAR GRS 1915+105 AND A REVISED ESTIMATE OF ITS BLACK HOLE MASS (2014, neutral): “◦37, where vLSR peaks at 70 km s−1 for R0 = 8.34 kpc and Θ0 = 240 km s−1 (Reid et al. 2014).”
• A geometric distance measurement to the Galactic center black hole with 0.3% uncertainty (2019, methodology): “For the third dimension, the motion along the Galactic plane, Reid et al. (2009) reported −7.2 ± 8.5 km s−1, and the update in Reid et al. (2014) implies tighter constraints around 2−3 km s−1.”
• Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18 (2019, background): “…the same values for the solar motion (U = 11.1 km s−1, V = 12.24 km s−1; Schönrich et al. 2010) and the distance to the Galactic Centre (8.34 kpc; Reid et al. 2014) as in Romero-Gómez et al. (2019), although the residual small-scale dipole variations close to the solar position suggest that…”
• Painting a portrait of the Galactic disc with its stellar clusters (2020, methodology): “We also computed the Galactocentric radius RGC, assuming a Solar Galactocentric distance of 8340 pc7, which is the value adopted by the spiral arm model of Reid et al. (2014).”