The Stellar Age-T eff-Kinematical Asymmetry in the Solar Neighborhood from LAMOST

With the velocity de-projection technique, we derived the averaged 3 dimensional local velocity distribution using only the line-of-sight velocity for the 200,000 FGK type main-sequence stars from the LAMOST DR1 data. Taking the effective temperature as a proxy for age, we investigate the variation of the velocity distribution as a function of T _eff and disk height within 100 < |z| < 500 pc. Using the mean velocities of the cool stars, we derive the solar motion of (U _⊙, V _⊙, W _⊙)=(9.58+/-2.39, 10.52+/-1.96, 7.01+/-1.67) kms^-1 with respect to the local standard of rest (LSR). Moreover, we find that the stars with T _eff > 6000 K show a net asymmetric motion of <U>~2 kms^-1 and <W>~3 kms^-1 compared to the stars with T _eff < 6000 K. And their azimuthal velocity increases when |z| increases. The asymmetric motion in the warmer stars is likely because they are too young and not completely relaxed.