| The star formation history in galaxies is intimately related to the galaxy evolution, as well as the evolution of central super-massive black hole. It was suggested that the star formation in circum-nuclear regions in Seyfert galaxies are suppressed. Syfert2galaxy, M51(NGC5194) is a nearby (8.4Mpc) nearly face-on Sbc spiral galaxy that hosts a weak active nucleus, which contributes to research the Star population composition. We obtain spatially resolved specific star formation rate (SSFR) in the inner-50pc for M51by analyzing spectra obtained with Hubble Space Telescope (HST) Space Telescope Imaging spectrograph (STIS) to investigate relation between the star formation rate in the circum-nuclear regions and the AGN.The main conclusions can be summarized as follows:(1)24radial spectra along the STIS long slit in M51are presented, extending-50pc from the nucleus (i.e.,-43.5pc to43.5pc).(2)By the simple stellar population synthesis, the stellar contributions in these radial optical spectra are modeled. It is found that the flux fraction of young stellar populations (younger than0.1Gyr) is about12%, the mass fraction is about0.11%. young stellar populations is not required in the center (from～6pc to2pc) in M51.(3)The young stellar populations is not required in the center inner～8pc in M51, suggested the possible SSFR suppression in the circum-nucleus region from the feedback of AGN.(4)The radial distribution of SSFR in M51seems to be not symmetrical in the direction along the STIS long slit. This unsymmetrical SSFR distribution is possibly due to the unsymmetrical AGN feedback in M51, related to its jet. |
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