1994A&A...287..463K

We investigated the globular cluster system (GCS) of the elliptical galaxy NGC 4636, for which a photographic study by Hanes (1977) already exists. NGC 4636 is situated in a low density outer region of the Virgo cluster of galaxies. We found a quite rich GCS of 3600±500 globular clusters (GCs). This corresponds to a specific frequency of S=7.5±2.0, slightly higher than the average for elliptical galaxies in the Virgo cluster (S≃6), but lower than S=9.9, which has been found by Hanes. Given the uncertainty of absolute S values, we cannot conclude that there is a real scatter of S values among Virgo and Fornax ellipticals. The turnover of the globular cluster luminosity function (GCLF) of NGC 4636 is at V=24.1±0.1 mag, equivalent to a distance modulus of (m-M)=31.2±0.3mag if we adopt a uniform absolute turnover magnitude for GCLFs in Virgo of -7.1±0.3mag. This distance is in good agreement with distances derived by other methods for NGC 4636. As already seen in some other galaxies with rich systems, the density profile of the globular clusters is clearly flatter than the light profile of the galaxy itself. The masses of the globular clusters follow a power law with an exponent of -1.9±0.1, similar to what is observed in the Milky Way and M31.