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Keywords:

  • stars: kinematics;
  • Galaxy: disc;
  • Galaxy: fundamental parameters;
  • Galaxy: kinematics and dynamics;
  • solar neighbourhood

ABSTRACT

We re-examine the stellar kinematics of the solar neighbourhood in terms of the velocity υ of the Sun with respect to the local standard of rest. We show that the classical determination of its component V in the direction of Galactic rotation via Strömberg's relation is undermined by the metallicity gradient in the disc, which introduces a correlation between the colour of a group of stars and the radial gradients of its properties. Comparing the local stellar kinematics to a chemodynamical model which accounts for these effects, we obtain (U, V, W)= (11.1+0.69−0.75, 12.24+0.47−0.47, 7.25+0.37−0.36) km s−1, with additional systematic uncertainties ∼(1, 2, 0.5) km s−1. In particular, V is 7 km s−1 larger than previously estimated. The new values of (U, V, W) are extremely insensitive to the metallicity gradient within the disc.