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Kinematics of the Milky Way Thick disk in solar neighborhood

K. Vieira

Instituto de Astronomía y Ciencias Planetarias, Universidad de Atacama, Copayapu 485, Copiapó 1531772, Chile

E-mail Address: [email protected]

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V. Korchagin

Institute of Physics, Stachki 194 Rostov-on-Don 344090, Russia

E-mail Address: [email protected]

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A. Lutsenko

Institute of Physics, Stachki 194 Rostov-on-Don 344090, Russia

E-mail Address: [email protected]

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https://doi.org/10.1142/S0218271821400101Cited by:0 (Source: Crossref)

This article is part of the issue:

SPECIAL ISSUE: Challenging Problems of Particle Physics and Astrophysics
Editor: Maxim Yu. Khlopov

Abstract

Using GAIA EDR3 catalog, we present the detailed analysis of the two-component Milky Way stellar disk in the solar neighborhood. To determine the kinematical properties of the thin and of the Thick disks, we select the complete sample of about 278,000 evolved red giant branch (RGB) stars distributed in the cylinder of 1 kpc radius and 0.5 kpc height centered at the Sun. We measured the following mean velocities and dispersions for the thin and the Thick disks, respectively: $(V_{R}, V_{ϕ}, V_{Z}) = (- 1, - 239, 0)$ km s $^{- 1}$ with $(σ_{R}, σ_{ϕ}, σ_{Z}) = (31, 20, 11)$ km s $^{- 1}$ , and $(V_{R}, V_{ϕ}, V_{Z}) = (+ 1, - 225, 0)$ km s $^{- 1}$ with $(σ_{R}, σ_{ϕ}, σ_{Z}) = (49, 35, 22)$ km s $^{- 1}$ . Errors in mean velocities and dispersions are all less than 1km s $^{- 1}$ . Same values were computed on much smaller subsamples of our Gaia data with RAVE DR5 [Fe/H] values, from which a metallicity selection was added. Results are basically the same. We find that up to 500 pc height above/below the galactic plane, Thick disk stars comprise about half the stars of the disk. We also find evidence of a substructure in $Z$ versus $V_{Z}$ in the thick disk population mostly that would give support to the accretion scenario for the formation of the thick disk.

Keywords:

PACS: 98.35.-a, 98.62.Dm, 98.35.Ac

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