Spatially integrated spectroscopy of the galactic H II regions M8.

We present preliminary results of new long slit (7.6 arcmin) optical (3700- 10 100 A) spatially integrated spectroscopic observations of a central portion of the galactic 11 II region M8, including the exciting star llD 164794 (O4V). With the slit of the telescope aligned N-S we "scanned" an area of 7.6 arcmin2. We extracted the spectra along the spatial direction, first including along with the nebular spectrum, the spectra of the exciting stars (case 1), and then excluding these stellar spectra (case 2). The line fluxes for the Balmer series are systematically bigger ( 2 to 8 %) in the case where the exciting stars have been excluded (case 2). The fluxes in the prominent [0 III] and [S III] lines are practically the same in both cases, while those of the [0 I], [0 II] and [N II] lines are smaller ( 2 to 6 %) in case 2 than in case 1. These small differences, if real, cause the model-assigned Effective Temperature for the nebula be 1 to 2 % cooler in case 2 with respect to case 1 and may have some consequences on analyses of giant extragalactic H II regions where the exciting stars are not resolved.