VizieR Online Data Catalog: Ionized nebulae in M31 (Walterbos+ 1992)

Deep CCD imagery in Hα and [SII] is presented of the major spiral arms of M31 with particular attention given to the data reduction and the analysis of the [SII]/Hα flux ratios. A diffuse ionized gas noted in the images is analyzed which shows higher [SII]/Hα ratios, and 967 discrete nebulae are listed with gray-scale images, finding charts, and absolute fluxes. The differential H-alpha luminosity function is found to have a slope of -0.95 for brighter objects and flattens out below a critical level. The curve is shown to correspond to the point at which single-star ionization accounts for the Hα luminosities and is consistent with previous observations. The catalog of objects and fluxes is the largest existing sample of this type, and the unresolved objects in the sample are considered to be planetary nebulae. (1 data file).