The stellar distribution and interstellar reddening in the Milky Way at l = 268 [degrees], b = 0 [degrees]

Abstract

This thesis presents a stellar space density analysis in the galactic plane at l = 268 [degree sign]. The data consist of photographic UBV photometry for 2461 stars and MK spectral classifications for 1713 of these. A colour-excess analysis reveals an absorption "wall" rising form A[subscript v](r) = 0[superscript m].8 to 3[superscript m].7 between r = 850 [degree sign] and 1350 pc. Beyond the dust cloud, there is little or no further extinction to a distance of at least 5 kpc from the Sun. Reduction of m-log [pie symbol] tables with Reed's iterative technique yields space distibutions consistent with those in other galactic plane fields. The stellar space densities variations show a remarkable generality among the various spectral groups. The stellar densities peak near 400 pc, decline to ~30% of the mean densities at 800 pc, and then increase again within the prominent dust cloud. Three OB associations are found at 1.15, 2.1 and 5.0 kpc, the furthest one possibly marking a distant spiral arm.