On the Rotation Speed of the Milky Way Determined from HI Emission

Abstract

The circular rotation speed of the Milky Way at the solar radius, Theta_o, has been estimated to be 220 km/s by fitting the maximum velocity of HI emission as a function of Galactic longitude. This result is in tension with a recent estimate of Theta_o=240 km/s, based on VLBI parallaxes and proper motions from the BeSSeL and VERA surveys for large numbers of high-mass star forming regions across the Milky Way. We find that the rotation curve best fitted to the VLBI data is slightly curved, and that this curvature results in a biased estimate of Theta_o from the HI data when a flat rotation curve is assumed. This relieves the tension between the methods and favors Theta_o=240 km/s.

arXiv comment4 figures

References in corpus (8)

• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• Monitoring stellar orbits around the Massive Black Hole in the Galactic Center
• 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 Milky Way's circular velocity curve between 4 and 14 kpc from APOGEE data
• Fundamental Parameters of the Milky Way Galaxy Based on VLBI astrometry
• Milky Way Kinematics: Measurements at the Subcentral Point of the Fourth Quadrant
• 3D stellar kinematics at the Galactic center: measuring the nuclear star cluster spatial density profile, black hole mass, and distance

Cited by in corpus (12)

• Rotation curve of the Milky Way from Classical Cepheids
• Kinematic Distances: A Monte Carlo Method
• The Hi-GAL catalogue of dusty filamentary structures in the Galactic Plane
• The spiral pattern rotation speed of the Galaxy and the corotation radius with GAIA DR2
• Recent advances in the determination of some Galactic constants in the Milky Way
• Tracing the Spiral Structure of the Outer Milky Way with Dense Atomic Hydrogen Gas
• Quantifying the (X/peanut)-shaped Structure of the Milky Way - New Constraints on the Bar Geometry
• On measuring the Galactic dark matter halo with hypervelocity stars
• Using Velocity Dispersion to Estimate Halo Mass: Is the Local Group in Tension with $\Lambda$CDM?
• Clustering of Local Group distances: publication bias or correlated measurements? V. Galactic rotation constants
• Impact of the Galactic Disk and Large Magellanic Cloud on the Trajectories of Hypervelocity Stars Ejected from the Galactic Center
• Spectroscopy of Dwarf Stars Around the North Celestial Pole