Three-Dimensional Kinematics of Classical Cepheids

A linear Ogorodnikov–Milne model is applied to study the three-dimensional kinematics of classical Cepheids in the Milky Way. A sample of 832 classical Cepheids from Mróz et al. (2019) with distances, line-of-sight velocities, and proper motions from the Gaia DR2 catalogue is used. The Cepheid space...

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Bibliographic Details
Published in:Astronomy letters 2021-09, Vol.47 (9), p.607-617
Main Authors: Bobylev, V. V., Bajkova, A. T.
Format: Article
Language:English
Subjects:
Angular velocity
Astronomy
Astrophysics and Astroparticles
Cepheid variables
Galactic rotation
Kinematics
Line of sight
Milky Way
Observations and Techniques
Physics
Physics and Astronomy
Stellar motions
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Summary:A linear Ogorodnikov–Milne model is applied to study the three-dimensional kinematics of classical Cepheids in the Milky Way. A sample of 832 classical Cepheids from Mróz et al. (2019) with distances, line-of-sight velocities, and proper motions from the Gaia DR2 catalogue is used. The Cepheid space velocities have been freed from the differential Galactic rotation found by us previously based on a nonlinear rotation model. Based on a complete Ogorodnikov–Milne model, involving the line-of-sight velocities and proper motions of stars, we have estimated the angular velocity of rotation around the Galactic axis, km s kpc . We think that this rotation is associated with the warp of the Galactic thin disk. Our calculations using only the proper motions of Cepheids under the assumption of no deformations due to the disk warp have shown the presence of a residual rotation around the axis with an angular velocity km s kpc and the presence of a positive rotation around the axis with an angular velocity km s kpc .
ISSN:1063-7737
1562-6873
DOI:10.1134/S1063773721090012