Ionized gas in the center of M 31.

H-alpha + forbidden N II, S II, and O III CCD images of the nuclear bulge of M31 are presented which show a striking spiral pattern of ionized gas extending to within a few parsecs of the nucleus. The mass of ionized gas is approximately 1500 solar masses and can easily be provided by mass lost from evolving stars. Comparison of the recombination rate with the ionizing flux expected from planetary nebula nuclei leads to the conclusion that evolved stars are insufficient to support the ionization. The filamentary appearance, small filling factor, and the strength of the forbidden S II lines suggest that some of the gas is heated by shocks. The geometry of the apparent spiral arms implies that much of the gas is in a plane which is tipped with respect to the disk of M31.