Probing the Circumnuclear Stellar Populations of Starburst Galaxies in
  the Near-infrared
  We employ the NASA Infrared Telescope Facility's near-infrared spectrograph
SpeX at 0.8-2.4$\mu$m to investigate the spatial distribution of the stellar
populations (SPs) in four well known Starburst galaxies: NGC34, NGC1614,
NGC3310 and NGC7714. We use the STARLIGHT code updated with the synthetic
simple stellar populations models computed by Maraston (2005, M05). Our main
results are that the NIR light in the nuclear surroundings of the galaxies is
dominated by young/intermediate age SPs ($t \leq 2\times10^9$yr), summing from
$\sim$40\% up to 100\% of the light contribution. In the nuclear aperture of
two sources (NGC1614 and NGC3310) we detected a predominant old SP component
($t > 2\times10^9$yr), while for NGC34 and NGC7714 the younger component
prevails. Furthermore, we found evidence of a circumnuclear star formation
ring-like structure and a secondary nucleus in NGC1614, in agreement with
previous studies. We also suggest that the merger/interaction experienced by
three of the galaxies studied, NGC1614, NGC3310 and NGC7714 can explain the
lower metallicity values derived for the young SP component of these sources.
In this scenario the fresh unprocessed metal poorer gas from the
destroyed/interacting companion galaxy is driven to the centre of the galaxies
and mixed with the central region gas, before star formation takes place. In
order to deepen our analysis, we performed the same procedure of SP synthesis
using Maraston (2011, M11) EPS models. Our results show that the newer and
higher resolution M11 models tend to enhance the old/intermediate age SP
contribution over the younger ages.
