We present the first speckle interferometric observations of R CrB , the prototype of a class of peculiar stars which undergo irregular declines in their visible light curves .
The observations were carried out with the 6 m telescope at the Special Astrophysical Observatory near maximum light ( V = 7 , 1996 Oct. 1 ) and at minimum light ( V = 10.61 , 1999 Sep. 28 ) .
A spatial resolution of 75 mas was achieved in the K -band .
The dust shell around R CrB is partially resolved , and the visibility is approximately 0.8 at a spatial frequency of 10 cycles/arcsec .
The two-dimensional power spectra obtained at both epochs do not show any significant deviation from circular symmetry .
The visibility function and spectral energy distribution obtained near maximum light can be simultaneously fitted with a model consisting of the central star and an optically thin dust shell with density proportional to r ^ { -2 } .
The inner boundary of the shell is found to be 82 R _ { \star } ( 19 mas ) with a temperature of 920 K. However , this simple model fails to simultaneously reproduce the visibility and spectral energy distribution obtained at minimum light .
We show that this discrepancy can be attributed to thermal emission from a newly formed dust cloud .