Unveiling the nature of M94's (NGC4736) outer region: a panchromatic
  perspective
  We have conducted a deep multi-wavelength analysis (0.15-160 mum) to study
the outer region of the nearby galaxy M94. We show that the non-optical data
support the idea that the outskirts of this galaxy is not formed by a closed
stellar ring (as traditionally claimed in the literature) but by a spiral arm
structure. In this sense, M94 is a good example of a Type III (anti-truncated)
disk galaxy having a very bright outer disk. The outer disk of this galaxy
contains ~23% of the total stellar mass budget of the galaxy and contributes
~10% of the new stars created showing that this region of the galaxy is active.
In fact, the specific star formation rate of the outer disk (~0.012 Gyr^{-1})
is a factor of ~2 larger (i.e. the star formation is more efficient per unit
stellar mass) than in the inner disk. We have explored different scenarios to
explain the enhanced star formation in the outer disk. We find that the inner
disk (if considered as an oval distortion) can dynamically create a spiral arm
structure in the outer disk which triggers the observed relatively high star
formation rate as well as an inner ring similar to what is found in this
galaxy.
