Stellar Populations in Barred Spirals


Simon Cantin


OASIS observations obtained at the CFHT for the spiral galaxies NGC4900 and NGC5430 produce one spectrum for each 0.41'' element of the 11''x15'' field of view. This allows for the spatial characterisation of different stellar populations. From these observations we study the young (~10 Myrs) and older stellar populations using evolutionary synthesis codes. Based on the gas emission lines, we find that the young populations peak in a relatively small central region that dominates the integrated flux. In NGC4900, the young population is located in a bar-like structure featuring a hole near the position of the galaxy\'s center. The young stellar population of NGC5430 is distributed along a nuclear ring. In this galaxy we also find patches of relatively older populations at the base of the spiral arms. Based on Mg and Fe absorption lines, we find that in both galaxies, the young stars are superimposed on a relatively homogenous population exhibiting an age of a few Gyrs.