  We present results from MUSE observations of the nearly face-on disk galaxy
NGC 7742. This galaxy hosts a spectacular nuclear ring of enhanced star
formation, which is unusual in that it is hosted by a non-barred galaxy, and
also because this star formation is most likely fuelled by externally accreted
gas that counter-rotates with respect to its main stellar body. We use the MUSE
data to derive the star-formation history (SFH) and accurately measure the
stellar and ionized-gas kinematics of NGC7742 in its nuclear, bulge, ring, and
disk regions. We map the previously known gas counter-rotation well outside the
ring region and deduce the presence of a slightly warped inner disk, which is
inclined ~6 degrees compared to the outer disk. The gas-disk inclination is
well constrained from the kinematics; the derived inclination 13.7 $\pm$ 0.4
degrees agrees well with that derived from photometry and from what one expects
using the inverse Tully-Fisher relation. We find a prolonged SFH in the ring
with stellar populations as old as 2-3 Gyr and an indication that the star
formation triggered by the minor merger event was delayed in the disk compared
to the ring. There are two separate stellar components: an old population that
counter-rotates with the gas, and a young one, concentrated to the ring, that
co-rotates with the gas. We recover the kinematics of the old stars from a
two-component fit, and show that combining the old and young stellar
populations results in the erroneous average velocity of nearly zero found from
a one-component fit. The superior spatial resolution and large field of view of
MUSE allow us to establish the kinematics and SFH of the nuclear ring in NGC
7742. We show further evidence that this ring has its origin in a minor merger
event, possibly 2-3 Gyr ago.
