Spectroscopic Confirmation of the Sixth Globular Cluster in the Fornax
  Dwarf Spheroidal Galaxy
  The Fornax dwarf spheroidal galaxy has an anomalous number of globular
clusters, five, for its stellar mass. There is a longstanding debate about a
potential sixth globular cluster (Fornax~6) that has recently been
`rediscovered' in DECam imaging. We present new Magellan/M2FS spectroscopy of
the Fornax~6 cluster and Fornax dSph. Combined with literature data we identify
$\sim15-17$ members of the Fornax~6 cluster that this overdensity is indeed a
star cluster and associated with the Fornax dSph. The cluster is significantly
more metal-rich (mean metallicity of $\overline{\rm [Fe/H]}=-0.71\pm0.05$) than
the other five Fornax globular clusters ($-2.5<[Fe/H]<-1.4$) and more
metal-rich than the bulk of Fornax. We measure a velocity dispersion of
$5.6_{-1.6}^{+2.0}\,{\rm km \, s^{-1}}$ corresponding to anomalously high
mass-to-light of 15$<$M/L$<$258 at 90\% confidence when calculated assuming
equilibrium. Two stars inflate this dispersion and may be either Fornax field
stars or as yet unresolved binary stars. Alternatively the Fornax~6 cluster may
be undergoing tidal disruption. Based on its metal-rich nature, the Fornax 6
cluster is likely younger than the other Fornax clusters, with an estimated age
of $\sim2$ Gyr when compared to stellar isochrones. The chemodynamics and star
formation history of Fornax shows imprints of major events such as infall into
the Milky Way, multiple pericenter passages, star formation bursts, and/or
potential mergers or interactions. Any of these events may have triggered the
formation of the Fornax~6 cluster.
