The inner $\sim$ 40 pc Radial Distribution of the Star formation Rate
  for a nearby Seyfert 2 galaxy M51
  We investigate spatially resolved specific star formation rate (SSFR) in the
inner $\sim$ 40 pc for a nearby Seyfert 2 galaxy, M51 (NGC 5194) by analyzing
spectra obtained with the \emph{Hubble Space Telescope (HST)} Space Telescope
Imaging Spectrograph (STIS). We present 24 radial spectra measured along the
STIS long slit in M51, extending $\sim 1\arcsec$ from the nucleus (i.e., -41.5
pc to 39.4 pc). By the simple stellar population synthesis, the stellar
contributions in these radial optical spectra are modeled. Excluding some
regions with zero young flux fraction near the center (from -6 pc to 2 pc), we
find that the mean flux fraction of young stellar populations (younger than
24.5 Myr) is about 9 \%, the mean mass fraction is about 0.09\%. The young
stellar populations are not required in the center inner $\sim$ 8 pc in M51,
suggesting a possible SSFR suppression in the circumnuclear region ($\sim$ 10
pc) from the feedback of active galactic nuclei (AGNs). The radial distribution
of SSFR in M51 is not symmetrical with respect to the long slit in STIS. This
unsymmetrical SSFR distribution is possibly due to the unsymmetrical AGN
feedback in M51, which is related to its jet.
