The local rotation curve of the Milky Way based on SEGUE and RAVE data

TL;DR

This study constructs the Milky Way's rotation curve near the Sun using SEGUE and RAVE data, revealing a smooth curve without evidence of a massive overdensity ring outside the solar radius.

Contribution

It provides a new detailed analysis of the local rotation curve and disc kinematics using recent large survey data, challenging previous claims of overdensity features.

Findings

The rotation curve is smooth between 7-10 kpc from the Galactic center.

No evidence supports a massive overdensity ring outside the solar radius.

Derived the radial scalelengths for different stellar populations.

Abstract

We construct the rotation curve of the Milky Way in the extended solar neighbourhood using a sample of SEGUE (Sloan Extension for Galactic Understanding and Exploration) G-dwarfs. We investigate the rotation curve shape for the presence of any peculiarities just outside the solar radius as has been reported by some authors. We approach the problem in a framework of classical Jeans analysis. Using the most recent data from RAVE (RAdial Velocity Experiment), we determine the solar peculiar velocity and the radial scalelengths for the three populations of different metallicities representing the Galactic thin disc. Then with the same binning in metallicity for the SEGUE G-dwarfs, we construct the rotation curve in the range of Galactocentric distances 7-10 kpc. We derive the circular velocity by correcting the mean tangential velocity for the asymmetric drift in each distance bin. With SEGUE data we also calculate the radial scalelength of the thick disc taking as known the derived peculiar motion of the Sun and the slope of the rotation curve. The rotation curve constructed through SEGUE G-dwarfs appears to be smooth in the selected radial range. The local kinematics of the thin disc rotation as determined in the framework of our new careful analysis does not favour the presence of a massive overdensity ring just outside the solar radius.