The Polar Stellar Ring and Dark Halo of NGC 5907
  Numerical simulations of the disruption of a dwarf companion moving in the polar plane of a massive galaxy are presented. The constructed model is compared with observational data on the recently discovered low-surface-brightness stellar ring around galaxy NGC 5907. Constraints on the ring lifetime (<=1.5 gyr after the first approach of the galaxies), on the structure of companion -- the ring presecursor, and on mass of dark halo of the main galaxy in whose gravitational field the companion moves are provided. The dark halo mass within 50 kpc of NGC 5907 center cannot exceed 3 or 4 "visible" masses. 
V.P.Reshetnikov, N.Ya.Sotnikova