A deep survey for Galactic Wolf-Rayet stars. II. Implications for Galacticstructure and massive star formation

We have completed a direct narrowband-broadband Schmidt plate survey of lar ge areas of the southern Milky Way for new Wolf-Rayet (W-R) stars as faint as 19th b magnitude. The 31 newly detected stars in the completed survey ar e among the reddest and/or most distant known in the Galaxy. We have obtain ed spectra of all candidate W-R stars in the 22 fields stretching from l = 282 degrees to l = 341 degrees in longitude and Delta b = 3.degrees 5 in la titude, covering about 180 square degrees. We also observed two isolated Mi lky Way fields centered at l = 0 degrees and l = 8 degrees. Eighteen new W- R stars are reported here for the first time. Combined with the 13 new W-R stars we have already reported in Carina, our list of 31 new Galactic W-R s tars reaches 3-4 mag fainter than previous surveys. Thirteen of our 18 new W-R stars reported here are of subtype WN, while five are of subtype WC. We present and describe their spectra and subtypes, derive their distances, a nd discuss the significance of their locations along with all other W-R sta rs in the Galaxy. Our new W-R stars clearly demonstrate an increasing numbe r ratio of WN to WC stars with increasing Galactocentric distance. We concl ude with predictions of the total number of Galactic W-R stars that should be discovered in future IR surveys.