Determination of the Galactic Rotation Curve from OB Stars

TL;DR

This study derives the Galactic rotation curve using three samples of OB stars, revealing detailed velocity field structures and refining key Galactic rotation parameters with high precision.

Contribution

It provides new measurements of the Galactic rotation parameters and demonstrates the influence of spiral density waves on stellar velocities.

Findings

Galactic rotation velocity at the solar distance is precisely determined.

Spiral density wave effects are evident in stellar velocity data.

The spectroscopic binary star sample yields the smallest errors in parameter estimation.

Abstract

We consider three samples of O- and B-type stars from the solar neighborhood 0.6--4 kpc for which we have taken the distances, line-of-sight velocities, and proper motions from published sources. The first sample contains 120 massive spectroscopic binaries. O stars with spectroscopic distances from Patriarchi et al. constitute the second sample. The third sample consists of 168 OB3 stars whose distances have been determined from interstellar calcium lines. The angular velocity of Galactic rotation at the solar distance $\Omega_0,$ its two derivatives $\Omega'_0$ and $\Omega"_0,$ and the peculiar velocity components of the Sun $(U,V,W)_\odot$ are shown to be well determined from all three samples of stars. They are determined with the smallest errors from the sample of spectroscopic binary stars and the sample of stars with the calcium distance scale. The fine structure of the velocity field associated with the influence of the Galactic spiral density wave clearly manifests itself in the radial velocities of spectroscopic binary stars and in the sample of stars with the calcium distance scale.