A SINFONI view of the nuclear activity and circum-nuclear star formation
  in NGC 4303
  We present new maps of emission-line flux distributions and kinematics in
both ionized (traced by HI and [FeII] lines) and molecular (H2) gas of the
inner 0.7x0.7kpc2 of the galaxy NGC4303, with a spatial resolution 40-80pc and
velocity resolution 90-150 km/s obtained from near-IR integral field
specroscopy using the VLT instrument SINFONI. The most promiment feature is a
200-250pc ring of circum-nuclear star-forming regions. The emission from
ionized and molecular gas shows distinct flux distributions: while the
strongest HI and [FeII] emission comes from regions in the west side of the
ring (ages~4Myr), the H2 emission is strongest at the nucleus and in the east
side of the ring (ages>10Myr). We find that regions of enhanced hot H2 emission
are anti-correlated with those of enhanced [FeII] and HI emission, which can be
attributed to post starburst regions that do not have ionizing photons anymore
but still are hot enough (~2000K) to excite the H2 molecule. The line ratios
are consistent with the presence of an AGN at the nucleus.
  The youngest regions have stellar masses in the range 0.3-1.5E5 MSun and
ionized and hot molecular gas masses of ~0.25-1.2E4 Msun and 2.5-5 Msun,
respectively. The stellar and gas velocity fields show a rotation pattern, with
the gas presenting larger velocity amplitudes than the stars, with a deviation
observed for the H2 along the nuclear bar, where increased velocity dispersion
is also observed, possibly associated with non circular motions along the bar.
The stars in the ring show smaller velocity dispersion than the surroundings,
that can be attributed to a cooler dynamics due to their recent formation from
cool gas.
