R Coronae Borealis
R Coronae Borealis ( R CrB short ) is an eruptive variable star in the constellation of the northern crown. R Coronae Borealis is a star of 6th magnitude, whose brightness drops at irregular intervals to the 14th magnitude.
R Coronae Borealis is a hydrogen- poor red supergiant with a carbon-rich atmosphere. The brightness of waste are probably due to emitted soot clouds that obscure the photosphere of the star. Thus, R Coronae Borealis is the prototype star for the same class of eruptive variable stars.