The ages and distances of globular clusters with the luminosity function method: the case of M5 and M55

Abstract

We present new age and distance determinations for the Galactic Globular Clusters M55 and M5, using the luminosity function method (Jimenez & Padoan 1996, Padoan & Jimenez 1997). We find an age of $11.8 \pm 1.5$ Gyr for M55 and $11.1 \pm 0.7$ Gyr for M5. This confirms previous results (Jimenez et al. 1996, Sandquist et al. 1996) and allows to conclude that the oldest stars in the Universe are not older than 14 Gyr. We also find $m-M=14.13 \pm 0.11$ for M55, and $m-M=14.49 \pm 0.06$ for M5. These values agree with the ones obtained using the tip of the red giant branch (Jimenez et al. 1996) and the sub-dwarf fitting method (Sandquist et al. 1996).