The strange case of the peculiar spiral galaxy NGC5474. New pieces of a
  galactic puzzle
  We present the first analysis of the stellar content of the structures and
substructures identified in the peculiar star-forming galaxy NGC5474, based on
Hubble Space Telescope resolved photometry from the LEGUS survey. NGC5474 is a
satellite of the giant spiral M101, and is known to have a prominent bulge that
is significantly off-set from the kinematic center of the underlying HI and
stellar disc. The youngest stars (age~ 100 Myr) trace a flocculent spiral
pattern extending out to ~8 kpc from the center of the galaxy. On the other
hand intermediate-age (age > 500 Myr) and old (age > 2 Gyr) stars dominate the
off-centred bulge and a large substructure residing in the South Western part
of the disc and not correlated with the spiral arms (SW over-density). The old
age of the stars in the SW over-density suggests that this may be another
signature of the dynamical interaction/s that have shaped this anomalous
galaxy. We suggest that a fly by with M101, generally invoked as the origin of
the anomalies, may not be sufficient to explain all the observations. A more
local and more recent interaction may help to put all the pieces of this
galactic puzzle together.
