* Astronomy

Title: High resolution spectroscopy of the BCD galaxy Haro 15: II. Chemodynamics
Authors: Guillermo F. Hagele (1,2,3), Veronica Firpo (1,2), Guillermo Bosch (1,2), Angeles I. Diaz (3), Nidia Morrell (4) ((1) Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de la La Plata, (2) IALP-Conicet, (3) Departamento de Fisica Teorica, Universidad Autonoma de Madrid, (4) Las Campanas Observatory, Carnegie Observatories)

We present a detailed study of the physical properties of the nebular material in four star-forming knots of the blue compact dwarf galaxy Haro 15. Using long-slit and echelle spectroscopy obtained at Las Campanas Observatory, we study the physical conditions (electron density and temperatures), ionic and total chemical abundances of several atoms, reddening and ionisation structure, for the global flux and for the different kinematical components. The latter was derived by comparing the oxygen and sulphur ionic ratios to their corresponding observed emission line ratios (the \eta and \eta' plots) in different regions of the galaxy. Applying the direct method or empirical relationships for abundance determination, we perform a comparative analysis between these regions. The similarities found in the ionisation structure of the different kinematical components implies that the effective temperatures of the ionising radiation fields are very similar in spite of some small differences in the ionisation state of the different elements. Therefore the different gaseous kinematical components identified in each star forming knot are probably ionised by the same star cluster. However, the difference in the ionising structure of the two knots with knot A showing a lower effective temperature than knot B, suggests a different evolutionary stage for them consistent with the presence of an older and more evolved stellar population in the first.

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