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SÉMINAIRE DU LERMA
OBSERVATOIRE DE PARIS
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Vendredi 11 Octobre 2002, à 14h, Paris, 77 avenue Denfert Rochereau, 14h


77 avenue Denfert Rochereau, Paris 14



Salle de l'Atelier, Observatoire de Paris





Heating and ionization in the Galactic Center



Nemesio RODRIGUEZ FERNANDEZ

Observatoire de Paris/LERMA



Résumé : Up to 10 % of the neutral gas of the Milky Way is concentrated in the central 500 pc of the Galaxy. In spite of the high gas surface density in the Galactic center (GC), the star formation rate is 10 times lower that that in the disk of the Galaxy. This is probably due to the particular conditions of the gas. The molecular clouds in the Galactic center are more turbulent, denser, and hotter than the clouds of the disk. In particular, the high temperatures are present over large regions where the dust is cold and apparently without associated ionized gas.
To study the physical conditions of the interstellar medium in the GC, and the heating of the molecular gas, we have observed a sample of clouds distributed all along the Galactic center. I will present ISO LWS/SWS observations of H2 pure rotational lines and fine-structure lines of several ions. With these observations we have been able to determine for the first time the total amount of warm molecular gas in the GC clouds. In addition, they have revealed the presence of a previously unknown ionized gas component. I will discuss how this findings give us further insight on the heating and the ionization of the GC interstellar medium.