Dust and Gas Correlations in the Region of the South Celestial Pole

About 20 years ago de Vaucouleurs (1955, 1960) drew attention to faint but extensive nebulosity in the region of the South Celestial Pole. He tentatively identified it as being emission nebulosity, excited by OB stars in the overlying galactic plane. The extent of these nebulae has become even more apparent in recent years on IIIa-J plates taken for the U.K. Schmidt survey of the southern sky. From a study of survey plates covering the sky south of declination 80° a map has been prepared of the nebulosity visible in the region. A study made of this ∽nebulosity suggests that it is predominantly reflection nebulosity, with the main source of illumination being integrated starlight of the overlying Carina spiral arm. The bulk of it is of very low surface brightness (fainter than about 26 mag. per square arcsec) and appears to be in the form of a broken layer underlying the local galactic plane at an altitude of ∽ 40–80 pc. There are a number of brighter nebulous patches and filaments, frequently highly structured on a scale of minutes of arc, and extending across several degrees, usually parallel to the galactic plane.