A direct measurement of the distance to the Galactic center using the kinematics of bar stars

Abstract

The distance to the Galactic center $R_0$ is a fundamental parameter for understanding the Milky Way, because all observations of our Galaxy are made from our heliocentric reference point. The uncertainty in $R_0$ limits our knowledge of many aspects of the Milky Way, including its total mass and the relative mass of its major components, and any orbital parameters of stars employed in chemo-dynamical analyses. While measurements of $R_0$ have been improving over a century, measurements in the past few years from a variety of methods still find a wide range of $R_0$ being somewhere within $8.0$ to $8.5\mathrm{kpc}$. The most precise measurements to date have to assume that Sgr A${}^{\ast }$ is at rest at the Galactic center, which may not be the case. In this paper, we use maps of the kinematics of stars in the Galactic bar derived from APOGEE DR17 and Gaia EDR3 data augmented with spectro-photometric distances from the \texttt{astroNN} neural-network method. These maps clearly display the minimum in the rotational velocity $v_T$ and the quadrupolar signature in radial velocity $v_R$ expected for stars orbiting in a bar. From the minimum in $v_T$, we measure $R_0=8.23\pm 0.12\mathrm{kpc}$. We validate our measurement using realistic $N$-body simulations of the Milky Way. We further measure the pattern speed of the bar to be ${\Omega }_{\mathrm{bar}}=40.08\pm 1.78{\mathrm{km}\mathrm{s}}^{-1}{\mathrm{kpc}}^{-1}$. Because the bar forms out of the disk, its center is manifestly the barycenter of the bar+disc system and our measurement is therefore the most robust and accurate measurement of $R_0$ to date.

References in corpus (69)

• Astropy: A Community Python Package for Astronomy
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• The 2.5 m Telescope of the Sloan Digital Sky Survey
• Local Kinematics and the Local Standard of Rest
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• The Galaxy in Context: Structural, Kinematic and Integrated Properties
• Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
• Measuring Distance and Properties of the Milky Way's Central Supermassive Black Hole with Stellar Orbits
• Trigonometric Parallaxes of High Mass Star Forming Regions: the Structure and Kinematics of the Milky Way
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• Trigonometric Parallaxes of Massive Star Forming Regions: VI. Galactic Structure, Fundamental Parameters and Non-Circular Motions
• Co-formation of the Galactic disc and the stellar halo
• Gaia Early Data Release 3: Parallax bias versus magnitude, colour, and position
• Detection of the gravitational redshift in the orbit of the star S2 near the Galactic centre massive black hole
• Mass models of the Milky Way
• Trigonometric Parallaxes Of High-Mass Star Forming Regions: Our View Of The Milky Way
• Gaia Data Release 2: Catalogue validation
• Reddening and Extinction Toward the Galactic Bulge from OGLE-III: The Inner Milky Way's Rv ~ 2.5 Extinction Curve
• A dynamically young and perturbed Milky Way disk
• The Effect of the Outer Lindblad Resonance of the Galactic Bar on the Local Stellar Velocity Distribution
• Relativistic redshift of the star S0-2 orbiting the Galactic center supermassive black hole
• An Update on Monitoring Stellar Orbits in the Galactic Center
• Vertical waves in the solar neighbourhood in Gaia DR2
• The Data Reduction Pipeline for the Apache Point Observatory Galactic Evolution Experiment
• Gaia Early Data Release 3 -- Catalogue validation
• The Milky Way's circular velocity curve between 4 and 14 kpc from APOGEE data
• Mapping the Three-Dimensional Density of the Galactic Bulge with VVV Red Clump Stars
• Target Selection for the Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• Dynamical modelling of the Galactic bulge and bar: the Milky Way's bar pattern speed, stellar, and dark matter mass distribution
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE) Spectrographs
• Galactic Rotation and Solar Motion from Stellar Kinematics
• Target Selection for the SDSS-IV APOGEE-2 Survey
• An Improved Distance and Mass Estimate for Sgr A* from a Multistar Orbit Analysis
• The mass distribution in the Galactic Centre from interferometric astrometry of multiple stellar orbits
• A Trigonometric Parallax of Sgr B2
• Life in the fast lane: a direct view of the dynamics, formation, and evolution of the Milky Way's bar
• Deep learning of multi-element abundances from high-resolution spectroscopic data
• Improved GRAVITY astrometric accuracy from modeling of optical aberrations
• Deciphering the 3D structure of the old Galactic bulge from the OGLE RR Lyrae stars
• Simultaneous calibration of spectro-photometric distances and the Gaia DR2 parallax zero-point offset with deep learning
• The pattern speed of the Milky Way bar from transverse velocities
• The Proper Motion of Sagittarius A*: III. The Case for a Supermassive Black Hole
• VVV Survey Near-Infrared Photometry of Known Bulge RR Lyrae stars: the Distance to the Galactic Center and Absence of a Barred Distribution of the Metal-Poor Population
• Constraints on the Galactic Bar from the Hercules stream as traced with RAVE across the Galaxy
• Revisiting the Tale of Hercules: how stars orbiting the Lagrange points visit the Sun
• Radial Distribution of Stellar Motions in Gaia DR2
• Characteristics of the Galaxy according to Cepheids
• Dynamics of a Massive Black Hole at the Center of a Dense Stellar System
• Signatures of resonance and phase mixing in the Galactic disc
• On the ridges, undulations & streams in Gaia DR2: Linking the topography of phase-space to the orbital structure of an N-body bar
• Gas dynamics in the Milky Way: a low pattern speed model
• Effects of baryonic and dark matter substructure on the Pal 5 stream
• The 4:1 Outer Lindblad Resonance of a long slow bar as a potential explanation for the Hercules stream
• Brownian Motion of Black Holes in Dense Nuclei
• Identifying resonances of the Galactic bar in Gaia DR2: I. Clues from action space
• A semi-analytic dynamical friction model for cored galaxies
• Gas Dynamics in the Galaxy: Total Mass Distribution and the Bar Pattern Speed
• The Parallax Zero-Point of Gaia Early Data Release 3 from LAMOST Primary Red Clump Stars
• A panoramic landscape of the Sagittarius stream in Gaia DR2 revealed with the STREAMFINDER spyglass
• Clustering of Local Group distances: publication bias or correlated measurements? IV. The Galactic Center
• Exploring the Sgr-Milky-Way-disc interaction using high resolution N-body simulations
• Stellar Abundance Maps of the Milky Way Disk
• Spectrophotometric parallaxes with linear models: Accurate distances for luminous red-giant stars
• Impacts of a Flaring Star-forming Disc and Stellar Radial Mixing on the Vertical Metallicity Gradient
• An extended Pal 5 stream in Gaia DR2
• Impact of basic angle variations on the parallax zero point for a scanning astrometric satellite
• Improving \textsl{Gaia} parallax precision with a data-driven model of stars
• Constraints on galileons from the positions of supermassive black holes

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• Gaia Data Release 3: Mapping the asymmetric disc of the Milky Way
• Dynamically constraining the length of the Milky Way bar
• Towards an astronomical foundation model for stars with a Transformer-based model
• A variational encoder-decoder approach to precise spectroscopic age estimation for large Galactic surveys
• The far side of the Galactic bar/bulge revealed through semi-regular variables
• A Bayesian estimation of the Milky Way's circular velocity curve using Gaia DR3
• Higgsino Dark Matter Confronts 14 years of Fermi Gamma Ray Data
• Dynamical friction and feedback on galactic bars in the general fast-slow regime
• Exploring the impact of a rapidly decelerating bar on transforming bulge orbits into disc-like orbits
• Bar-driven dispersal of Galactic substructure
• 3D structure of the Milky Way out to 10 kpc from the Sun. Catalogue of large molecular clouds in the Galactic Plane
• Accelerated phase-mixing in the stellar halo due to a rotating bar
• VVV catalog of ab-type RR Lyrae in the inner Galactic bulge
• The Galactic Bulge exploration IV.: RR~Lyrae stars as traces of the Galactic bar -- 3D and 5D analysis, extinction variation
• Modeling the Cosmic Dispersion Measure in the D < 120 Mpc Local Universe
• First measurement of the triaxiality of the inner dark matter halo of the Milky Way
• Dynamical streams in the local stellar halo
• Estimation of the Galactocentric Distance of the Sun from Cepheids Close to the Solar Circle
• On the Fast Track: Rapid construction of stellar stream paths
• On the origin of the Hercules group: I. chemical signatures indicating the outer bar origin
• Constraints on the origins of the Galactic neutrino flux
• Metallicity Structure in Galactic Longitude-Velocity Diagrams of the Milky Way Disk and FIRE-2 Simulations
• The potential of diffuse Galactic Ridge neutrino measurements to constrain dark matter
• Dynamical properties of high-[Mg/Fe] stars in the Milky Way bar region
• On the Nature of the Protoplanetary Nebula OH\,231.8+4.2