We present an analysis of the globular cluster ( GC ) system of the nucleated dwarf elliptical galaxy VCC 1087 in the Virgo cluster , based on Keck/LRIS spectroscopy and archival Hubble Space Telescope /Advanced Camera for Surveys imaging .
We estimate VCC 1087 hosts a total population of 77 \pm 19 GCs , which corresponds to a relatively high V -band specific frequency of 5.8 \pm 1.4 .
The g _ { \thinspace 475 } - z _ { \thinspace 850 } color distribution of the GCs shows a blue ( metal-poor ) peak with a tail of redder ( metal-rich ) clusters similar in color to those seen in luminous ellipticals .
The luminosity function of the GCs is log-normal and peaks at M _ { g _ { \thinspace 475 } } ^ { TO } = -7.2 \pm 0.3 , M _ { z _ { \thinspace 850 } } ^ { TO } = -8.1 \pm 0.2 .
These peak positions are consistent with those found for luminous Virgo ellipticals , suggesting either the lack of , or surprisingly similar , dynamical destruction processes of GCs among dwarf and giant galaxies .
Spectroscopy of a subsample of 12 GCs suggests that the GC system is old and coeval ( ~ { } \hbox to 0.0 pt { $ > $ } { \lower 4.3 pt \hbox { $ \sim$ } } 10 Gyr ) , with a fairly broad metallicity distribution ( –1.8 ~ { } \hbox to 0.0 pt { $ < $ } { \lower 4.3 pt \hbox { $ \sim$ } } [ m/H ] ~ { } \hbox to 0.0 pt { $ < $ } { \lower 4.3 pt \hbox { $ \sim$ } } –0.8 ) .
In contrast , an integrated spectrum of the underlying galaxy starlight reveals that its optical luminosity is dominated by metal-rich , intermediate-aged stars .
Radial velocities of the GCs suggest rotation close to the major axis of the galaxy , and this rotation is dynamically significant with ( v _ { rot } / \sigma _ { los } ) ^ { * } > 1 .
A compilation of the kinematics of the GC systems of 9 early-type galaxies shows surprising diversity in the ( v _ { rot } / \sigma _ { los } ) parameter for GC systems .
In this context , the GC system of VCC 1087 exhibits the most significant rotation to velocity dispersion signature .
Dynamical mass modeling of the velocity dispersion profile of the GCs and galaxy stars suggest fairly constant mass-to-light ratios of \sim 3 out to 6.5 kpc .
The present observations can entertain both baryonic and non-baryonic solutions , and GC velocities at larger radii would be most valuable with regard to this issue .
Finally , we discuss the evolution of VCC 1087 in terms of the galaxy “ harassment ” scenario , and conclude that this galaxy may well be the remains of a faded , tidally perturbed Sc spiral .