MAPPING OF R CRB DUST SHELLS

the aim of this proposal is to investigate fossil dust shells around members of the class of r crb stars, following the discovery, using iras, of a very large cool dust shell around r crb itself, and possibly one around su tau. the parameters of the r crb dust shell are very uncertain, but they are not inconsistent with the evolutionary scenario for r crb. the original iras data suggested that not all r crb stars might have this cool fossil shell, so that a more sensitive survey of the stars is needed. since the fossil shells were only visible at 60um and 100um with iras, only iso can further investigate the phenomenon. the dust temperature was estimated at 25 30 k. the size of the fossil shell around r crb was about 20 arcmin, so that mapping is needed. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]