Published in "The Extragalactic Distance Scale", eds. M Livio, M. Donahue and N. Panagia, Cambridge University Press 1997.
For a postscript version of the article, click here.
Abstract. The globular cluster luminosity function (GCLF) for
bright elliptical galaxies can be approximately
represented as a Gaussian distribution, with a mean value
M0V = -7.21 ± 0.26 mag and
a width = 1.35 ± 0.05
mag. Most of the uncertainty in M0V is due to the
Cepheid distance
scale to the Virgo cluster used to determine the zeropoint. The
intrinsic dispersion in M0V is
0.12 mag for bright
ellipticals, making it competitive with the best distance
indicators. The value of M0V appears to be nearly
universal, with only a weak second-order dependence on
luminosity clearly demonstrated and other second-order dependencies
possible at about the 0.1 - 0.2
mag level (e.g. Hubble type, color, and environment). The Hubble
Space Telescope provides
a significant improvement in our ability to measure
M0V, with limiting magnitudes for one orbit
observations more than two magnitudes beyond the turnover in the GCLF
for galaxies in the Virgo cluster. Historical estimates of the Hubble
constant based on the GCLF have been
surprisingly stable for nearly 30 years, with a mean
H0 = 72 km s-1 Mpc-1. At present
the best estimate can probably be determined using seven galaxies in the
Fornax cluster, yielding a value
of H0 = 82 ± 13 km s-1
Mpc-1. Several hundred high quality GCLF's should be
published in the next few years, making globular clusters one of the
most important distance indicators during the next decade.
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