Estimation of the SolarGalactocentric Distance and Rotation Velocity from Near-Solar-Circle Objects

TL;DR

This study refines estimates of the solar Galactocentric distance and Galactic rotation velocity using near-solar-circle objects, accounting for spiral density wave perturbations, and compares different proper motion data sources.

Contribution

It introduces a modified method for estimating R_0 and V_0 that incorporates spiral density wave effects and compares results using different stellar proper motion catalogs.

Findings

Estimated R_0 from star-forming regions: 7.25±0.32 kpc.

Estimated R_0 and V_0 from Cepheids with P>5d: 7.66±0.36 kpc and 267±17 km/s.

Different proper motion catalogs yield consistent R_0 but varying V_0 estimates.

Abstract

We have tested the method of determining the solar Galactocentric distance R_0 and Galactic rotation velocity $V_0$ modified by Sofue et al. using near-solar-circle objects. The motion of objects relative to the local standard of rest has been properly taken into account. We show that when such young objects as star-forming regions or Cepheids are analyzed, allowance for the perturbations produced by the Galactic spiral density wave improves the statistical significance of the estimates. The estimate of R_0=7.25\pm0.32 kpc has been obtained from 19 star-forming regions. The following estimates have been obtained from a sample of 14 Cepheids (with pulsation periods P>5^d): R_0=7.66\pm0.36 kpc and V_0=267\pm 17 km s^{-1}. We consider the influence of the adopted Oort constant A and the character of stellar proper motions (Hipparcos or UCAC4). The following estimates have been obtained from a sample of 18 Cepheids with stellar proper motions from the UCAC4 catalog: R_0=7.64\pm0.32 kpc and V_0=217\pm 11 km s^{-1}.