Reddening and dust distribution around V348 SGR

Abstract

Radio and Brackett gamma observations indicate large value of reddening E(B - V) = 1.5 to the nebula surrounding V348 Sgr, where as the star appears to be reddened by only E(B - V) is approximately 0.4. The infrared observations both ground based and with IRAS show that there are two dust components present: the hot dust represented by a 600 K black body longward of 3.5 micron and another cool dust (100 K or less) black body. The hot dust extends to about 6 arcsec radius from the star. The cool dust component surrounds the nebula and probably is responsible for the high extinction in the nebula. A tilted hollow cylinder or a tilted disk with a cavity type structure seems to be needed to account for the lack of reddening toward the star. Similarities of the nebular and dust properties of V348 Sgr and R Cr B indicate that they are approaching the red giant stage for a second time.