Variation of the galactic force law in the region of the sun

Abstract

From the radial velocity data for O-B5 stars within 3 kpc of the Sun the variation of the semi-axes Σ₁ and Σ₂ of the velocity ellipsoid in the solar region is estimated. It is found that both the semi-axes as well as their ratio Σ₂/Σ₁ decrease away from the galactic centre. The value of Σ₂/Σ₁ changes from 1.17 at R=9 kpc to 0.48 atR=11 kpc passing through a value of 0.86 at the solar distance of R₀=10 kpc. These results are consistent with the usually assumed inverse square law of force in the outer regions of the galaxy.