The globular cluster system of NGC 1316. II - The extraordinary object
  SH2
  SH2 has been described as an isolated HII-region, located about 6.5 arcmin
south of the nucleus of NGC 1316 (Fornax A), a merger remnant in the the
outskirts of the Fornax cluster of galaxies. We give a first, preliminary
description of the stellar content and environment of this remarkable object.
We used photometric data in the Washington system and HST photometry from the
Hubble Legacy Archive for a morphological description and preliminary aperture
photometry. Low-resolution spectroscopy provides radial velocities of the
brightest star cluster in SH2 and a nearby intermediate-age cluster. SH2 is not
a normal HII-region, ionized by very young stars. It contains a multitude of
star clusters with ages of approximately 0.1 Gyr. A ring-like morphology is
striking. SH2 seems to be connected to an intermediate-age massive globular
cluster with a similar radial velocity, which itself is the main object of a
group of fainter clusters. Metallicity estimates from emission lines remain
ambiguous. The present data do not yet allow firm conclusions about the nature
or origin of SH2. It might be a dwarf galaxy that has experienced a burst of
extremely clustered star formation. We may witness how globular clusters are
donated to a parent galaxy.
