| Author(s): | Wielen, R., Fuchs, B., Dettbarn, C., Jahreiß, H., Rockmann, J. |
| Title: | Kinematics of RR Lyrae stars based on HIPPARCOS proper motions |
| Source: | In: B. Battrick, M.A.C. Perryman and P.L. Bernacca (eds.): HIPPARCOS '97. Presentation of the Hipparcos and Tycho catalogues and first astrophysical results of the Hipparcos space astrometry mission, Venice, Italy, 13-16 May 1997; ESA SP-402, Noordwijk, p. 599-602 |
| Year: | 1997 |
| Abstract: | We have derived the galactic space velocities of 130 RR Lyrae stars, using proper motions measured by HIPPARCOS. The distances of the stars are taken from a photometric calibration which is confirmed by HIPPARCOS parallaxes. We present the mean velocities and the velocity dispersions of the RR Lyrae stars as a function of the metallicity [Fe/H]. The data do not allow to decide safely whether the kinematical properties of halo and disk objects show a smooth transition or wheter halo and disk stars belong to two distinct populations. The difference in the mean motions of metal-poor and metal-rich RR Lyrae stars is in good agreement with a circular velocity of about 220 km/s at the Sun. Adopting such a circular velocitry, the system of metal-poor RR Lyrae stars shows no significant net rotation in our Galaxy. The metal-rich RR Lyrae stars move like typical disk stars. |
| Preprint issued: | June 1997 |
| Remarks: |
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