LBT/MODS spectroscopy of globular clusters in the irregular galaxy NGC
  4449
  We present intermediate-resolution (R$\sim$1000) spectra in the
$\sim$3500-10,000 A range of 14 globular clusters in the magellanic irregular
galaxy NGC 4449 acquired with the Multi Object Double Spectrograph on the Large
Binocular Telescope. We derived Lick indices in the optical and the
CaII-triplet index in the near-infrared in order to infer the clusters' stellar
population properties. The inferred cluster ages are typically older than
$\sim$9 Gyr, although ages are derived with large uncertainties. The clusters
exhibit intermediate metallicities, in the range
$-1.2\lesssim$[Fe/H]$\lesssim-0.7$, and typically sub-solar [$\alpha/Fe$]
ratios, with a peak at $\sim-0.4$. These properties suggest that i) during the
first few Gyrs NGC 4449 formed stars slowly and inefficiently, with galactic
winds having possibly contributed to the expulsion of the $\alpha$-elements,
and ii) globular clusters in NGC 4449 formed relatively "late", from a medium
already enriched in the products of type Ia supernovae. The majority of
clusters appear also under-abundant in CN compared to Milky Way halo globular
clusters, perhaps because of the lack of a conspicuous N-enriched,
second-generation of stars like that observed in Galactic globular clusters.
Using the cluster velocities, we infer the dynamical mass of NGC 4449 inside
2.88 kpc to be M($<$2.88 kpc)=$3.15^{+3.16}_{-0.75} \times 10^9~M_\odot$. We
also report the serendipitous discovery of a planetary nebula within one of the
targeted clusters, a rather rare event.
