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   PR # 41244
   Recent observations show the stars in cD envelope consist of
   considerably old population as host galaxy. If cD envelope is formed
   by stripping , interactions have to take place at begining phase of
   cluster evolution. Scombert(1988) suggested that luminosity of cD
   envelope have good corelation with X ray luminosty of its cluster .
   This result directly indicate a connection between cluster potential
   and developement of cD galaxy. The terget of this observation A779
   have bright cD galaxy (Mv=-23.2), but have very faint cD envelope,
   which luminosity is 2 order of magnitude fainter than average X ray
   luminous clusters. This observation will show us effects of cluster
   potential to cD envelope. And reveal evolutional history of cD
   galaxy.
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