The globular cluster system in the inner region of M87

We have identified 1057 globular cluster candidates in a WFPC2 image of the inner region of M87. The globular cluster luminosity function (GCLF) can b e well fitted by a Gaussian profile with a mean value of m(V)(0) = 23.67 +/ - 0.07 mag and sigma = 1.39 +/- 0.06 mag. The GCLF in five radial bins is f ound to be statistically the same at all points, showing no clear evidence of dynamical destruction processes based on the luminosity function (LF). S imilarly, there is no obvious trend between the half-light radius of the cl usters and the galactocentric distance. The core radius of the globular clu ster density distribution is R-c = 56 ", considerably larger than the core of the stellar component (R-c = 6 ".8). The mean color of the cluster candi dates is V-I = 1.09 mag, which corresponds to an average metallicity of Fe/ H = -0.74 dex. The color distribution is bimodal everywhere, with a blue pe ak at V-I = 0.95 mag and a red peak at V-I = 1.20 mag. The red population i s only 0.1 mag bluer than the underlying galaxy, indicating that these clus ters formed late in the metal-enrichment history of the galaxy and were pos sibly created in a burst of star/cluster formation 3-6 Gyr after the blue p opulation. We also find that both the red and the blue duster distributions have a more elliptical shape (Hubble type E3.5) than the nearly spherical galaxy. The average half-light radius of the clusters is approximate to 2.5 pc, which is comparable to the 3 pc average effective radius of the Milky Way clusters, although the red clusters are approximate to 20% smaller than the blue ones.