The Smallest Scale of Hierarchy Survey (SSH). II. Extended star
  formation and bar-like features in the dwarf galaxy NGC 3741: recent merger
  or ongoing gas accretion?
  Using Large Binocular Telescope deep imaging data from the Smallest Scale of
Hierarchy Survey (SSH) and archival Hubble Space Telescope data, we reveal the
presence of two elongated stellar features contiguous to a bar-like stellar
structure in the inner regions of the dwarf irregular galaxy NGC 3741. These
structures are dominated by stars younger than a few hundred Myr and
collectively are about twice as extended as the old stellar component. These
properties are very unusual for dwarf galaxies in the nearby Universe and
difficult to explain by hydro-dynamical simulations. From the analysis of
archival 21-cm observations, we find that the young stellar "bar" coincides
with an HI high-density region proposed by previous studies to be a purely
gaseous bar; we furthermore confirm radial motions of a few km/s, compatible
with an inflow/outflow, and derive a steeply-rising rotation curve and high HI
surface density at the center, indicating a very concentrated mass
distribution. We propose that the peculiar properties of the stellar and
gaseous components of NGC 3741 may be explained by a recent merger or ongoing
gas accretion from the intergalactic medium, which caused gas inflows towards
the galaxy center and triggered star formation a few hundred Myr ago. This
event may explain the young and extended stellar features, the bar-like
structure, the very extended HI disc and the central HI spiral arms. The high
central HI density and the steeply rising rotation curve suggest that NGC 3741
may be the progenitor or the descendant of a starburst dwarf.
