Mass segregation in M 67 with 2MASS

Universidade Federal do Rio Grande do Sul, Instituto de Física, CP  15051, Porto Alegre 91501-970, RS, Brazil

Corresponding author: Ch. Bonatto, charles@if.ufrgs.br

Received: 9 December 2002
Accepted: 10 February 2003

Abstract

We make use of the homogeneity, depth and sky coverage of the 2MASS catalogue to study spatial variations of the stellar luminosity function in the intermediate age cluster M 67 (NGC 2682). We find that the central region () has a depletion of G 0 and G 5 stars with respect to the intermediate annulus () and the halo (). In the non-eroded part of the mass function the slope is steeper in the intermediate annulus than in the central region, suggesting an enhancement of F 0 stars with respect to turnoff and A 5 stars in the latter zone. In the halo, the G 0–G 5 stars are not depleted as compared to the central region, but the overall mass function slope is rather shallow. This suggests that the halo is enriched in low mass stars, transferred there from the inner parts as a consequence of the internal dynamical evolution, but tidal losses to the Galactic field have also been important.