The Initial Mass Function of Low-Mass Stars in Globular Clusters

摘要

We compare deep I-band luminosity functions of two globular clusters (NGC 6397 and NGC 6656) that have similar metal content but have experienced very different dynamical histories, both in terms of internal dynamics and as a result of different interactions with the Galactic tidal field. Their luminosity functions measured at the half-mass radius are indistinguishable from one another within the statistical errors over a range of more than 5 mag. They both show an increase with decreasing luminosity up to a peak at M_1 ≈ 8.5 and then drop all the way to the detection limit.