BIDIMENSIONAL SPECTROSCOPY OF NGC-4214 - EVOLUTIONARY STATE AND INTERSTELLAR EXTINCTION

We have mapped spectrophotometrically the star-forming regions in the center of the nearby SBm galaxy NGC 4214 with the aim of analyzing the spatial distribution of some of its physical properties (density, exc itation, emission line intensity, extinction) and their relationship w ith the distribution and evolutionary state of the stellar population. Star formation takes place mainly in two big complexes, although seve ral smaller star-forming regions spread over the central bar of the ga laxy have also been identified. The comparison of different observable parameters (W(H beta), Wolf-Rayet population, effective temperature, UV absorption lines) with the predictions of synthesis models provides a consistent picture in which the different star formation episodes t ook all place around 3 Myr ago, with a very narrow spread in time (in any case within 1 Myr). The brightest star forming complex, located at the visible nucleus of the galaxy, is apparently the most evolved one . The surrounding interstellar medium is being disrupted, with a clear spatial decoupling between stars, gas and dust clouds. The dust appea rs concentrated at the boundaries of the ionized region, affecting mai nly the nebular emission lines, while the stellar continuum itself is located in a region relatively free of dust and gas. This decoupling m ay explain the differences in extinction found previously between the stellar continuum and the emission lines. On the other hand, the ioniz ed gas is essentially co-spatial with the massive stellar clusters in the SE complex, which apparently is less evolved. Nevertheless, the du st tends to be concentrated in isolated clouds located generally at th e boundaries of the line emitting nebulae. We postulate that stellar w inds have contributed to concentrate these dust particles in the inter -cluster medium.