Abstract
We present HST observations of the lower main sequence of the Galactic globular cluster M3. Our data, obtained with WFPC2 in the F814W and F555W filters, sample a region centred about 4 arcmin away from the cluster centre (at ∼4.2 core radii). The photometry of the WF2, WF3 and WF4 fields extends down to V∼26.5 (I∼25), much deeper than any previous ground-based study on this cluster. The resulting luminosity function (LF) for the main sequence covers the interval MI=3–10.5, and reaches a maximum between MI=8.5 and 9, sharing in this feature the same behaviour as other clusters studied with HST so far. Making use of four different mass–luminosity (M–L) relations (theoretical and semi-empirical) a present-day mass function (MF) has also been obtained, which spans the mass interval ≃0.8–0.18 M⊙. Independent of the adopted M–L relation, the MF clearly flattens out at the low-mass limits. However, no attempt has been made to take into account possible effects due, for instance, to mass segregation and evaporation.
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