Galactic Kinematics from a Sample of Young Massive Stars

Abstract

Based on published sources, we have created a kinematic database on 220 massive (>10 solar masses) young Galactic star systems located within <3 kpc of the Sun. Out of them, approximately 100 objects are spectroscopic binary and multiple star systems whose components are massive OB stars; the remaining objects are massive Hipparcos B stars with parallax errors of no more than 10 percent. Based on the entire sample, we have constructed the Galactic rotation curve, determined the circular rotation velocity of the solar neighborhood around the Galactic center at Ro=8 kpc, Vo=259+-16 km/s, and obtained the following spiral density wave parameters: the amplitudes of the radial and azimuthal velocity perturbations f_R=-10.8+/-1.2 km/s, and f_θ=7.9+/-1.3 km/s, respectively; the pitch angle for a two-armed spiral pattern i=-6.0+/-0.4 deg., with the wavelength of the spiral density wave near the Sun being 2.6+/-0.2 kpc; and the radial phase of the Sun in the spiral density wave -120+/-4 deg. We show that such peculiarities of the Gould Belt as the local expansion of the system, the velocity ellipsoid vertex deviation, and the significant additional rotation can be explained in terms of the density wave theory. All these effects decrease noticeably once the influence of the spiral density wave on the velocities of nearby stars has been taken into account. The influence of Gould Belt stars on the Galactic parameter estimates has also been revealed. Eliminating them from the kinematic equations has led to the following new values of the spiral density wave parameters: f_θ=2.9+/-2.1 km/s and χ_\odot=-104+/-6 deg.

25 pages, 9 figures, 3 tables

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Cited by in corpus (17)

• The Milky Way Spiral Structure Parameters from Data on Masers and Selected Open Clusters
• Galactic masers: kinematics, spiral structure and the disk dynamic state
• Galactic Rotation Curve and Spiral Density Wave Parameters from 73 Masers
• The local standard of rest from data on young objects with account for the Galactic spiral density wave
• Determination of the Galactic Rotation Curve from OB Stars
• The Gould Belt, the de Vaucouleurs-Dolidze Belt, and the Orion Arm
• The Galaxy Kinematics from OB Stars with Proper Motions from the Gaia DR1 Catalog
• Determination of Galactic Rotation Parameters and the Solar Galactocentric Distance Ro from 73 Masers
• Kinematics of the Galaxy from OB Stars with Data from the Gaia DR2 Catalogue
• Kinematics of the Galaxy from a Sample of Young Open Star Clusters with Data from the Gaia DR2 Catalogue
• Galactic Kinematics from Data on Open Star Clusters from the MWSC Catalogue
• New Expansion Rate Estimate of the Scorpius-Centaurus Association Based on T Tauri Stars from the Gaia DR2 Catalog
• The Science of Fundamental Catalogs
• Search for Kinematic Siblings of the Sun Based on Data from the XHIP Catalog
• Kinematics of T Tauri Stars Close to the Sun from the Gaia DR2 Catalogue
• A new estimate of the Local Standard of Rest from data on young Galactic objects
• Determination of the Solar Galactocentric distance from masers kinemics