Kinematics and M-V calibration of K & M dwarf stars using Hipparcos data

We present a new determination of the luminosities and kinematics of lower main sequence stars in the spectroscopically selected sample of Vyssotsky, covering spectral types from K3 to M5, using Hipparcos parallaxes and proper motions. The stars separate into two kinematically distinct components, which we label 'young' and 'old' disk. The young component has velocity dispersion (30, 17, 12) km s(-1) in the UVW directions respectively, asymmetric drift of 8 km s(-1), a marginally significant vertex deviation of 10 deg +/-3 deg, and absolute magnitude M-V = 10.48 at color (R - I)(Kron) = 1.0 mag. The old component has velocity dispersions (56, 34, 31) km s(-1), asymmetric drift 28 km/s, and absolute magnitude 0.6 mag fainter at the same color. The slope and intrinsic width of the magnitude calibration of each component are also determined. All results are in agreement with previous determinations using ground-based data, but the errors are considerably smaller. The analysis is also used to investigate the possible presence of residual systematic discrepancies of the model with Hipparcos observations. There is some indication of a possible underestimate of the parallax errors, but the sample used here is too small for a positive determination.