Estudio de la asociación I Canis Majoris

Abstract

In the belt (6ʰ48ᵐ< AR < 7ʰ12ᵐ, — 8° > D > —12°) early-type stars (O , BO, B3, B5) are predominant and a group of early-type stars with slightly higher concentration than in the rest of the Milky Way is found in Canis Majoris. 15 stars were classified in the M.K.K. system: 5 are late-type main sequence stars probably in the foreground, the remaining 10 being possible members. None of the obtained spectra show emission lines. The study of proper motions of 79 stars shows a strong mean motion perpendicular to the galactic plane. A distance of 1550 pc was obtained assuming a mean absorption of 0ᵐ3 in the whole region. The distance derived by statistical parallaxes is incompatible with the preceding value; this fact shows the existence of appreciable systematic motions with respect to the Sun. It was not possible to improve the distance by using the galactic rotation curve.