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Structure and kinematics of the Milky Way spirals traced by open clusters†

Published online by Cambridge University Press:  01 October 2007

Z. Zhu
Z. Zhu*
Affiliation:
Department of Astronomy, Nanjing University, China email: zhuzi@nju.edu.cn
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Abstract

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Selecting 301 open clusters with complete spatial velocity measurements and ages, we are able to estimate the disk structure and kinematics of the Milky Way. Our analysis incorporates the disk scale height, the circular velocity of the Galactic rotation, the Galactocentric distance of the Sun and the ellipticity of the weak elliptical potential of the disk. We have derived the distance of the Sun to the Galactic center R0=8.03±0.70 kpc, that is in excellent agreement with the literature. From kinematic analysis, we found an age-dependent rotation of the Milky Way. The mean rotation velocity of the Milky Way is obtained as 235±10 km s−1. Using a dynamic model for an assumed elliptical disk, a clear weak elliptical potential of the disk with ellipticity of ε(R0) = 0.060±0.012 is detected, the Sun is found to be near the minor axis with a displacement of 30°±3°. The motion of clusters is suggested to be on elliptical orbits other than the circular rotation.

Keywords

Galaxy: diskastrometryGalaxy: kinematics and dynamicsGalaxy: structureopen clusters and associations: general
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 3 , Symposium S248: A Giant Step: from Milli- to Micro-arcsecond Astrometry , October 2007 , pp. 462 - 465
Copyright
Copyright © International Astronomical Union 2008

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