The age and kinematic distributions of the Milky Way stellar halo

We measure largely unknown, the mean azimuthal velocity ($v_{rot}$ ), velocity anisotropy ($β$), and velocity dispersions ($σ_r , σ_θ , σ_φ$ ) parameters of the Milky Way halo stars within the galactocentric radial distance, r <=15 kpc. We find that the metal-poor ([Fe/H]≤ −1.4) and metal-rich ([Fe/H]> −1.4) of Main Sequence Turn-off (MSTO) sample have kinematic bias, i.e. the retrograde and the prograde motion, with the mean difference in their $v_{rot}$ of roughly 40 km/s . In the case of K-Giant stars (KGs) sample, the metallicity bias in kinematics is negligible; so the distinction, in this case, is not clear-cut. Within r <=15 kpc, our sample population MSTOs, and KGs show radially biased. i.e. $σ_r$ > $σ_θ$ or $σ_φ$ with $β$ ~0.5.