WHAT IS NEW ABOUT THE NEW COMET YANAKA (1988R)

A deficiency in the observed abundances of C2 and CN in comet Yanaka ( 1988r) is explained in terms of the properties of its organic refracto ry dust component and the fact that it is a new comet. Because the maj or fraction of the carbon in comets is in a mixture of complex organic molecules which earlier explained the ''missing'' carbon mystery it i s shown that substantial carbon depletions are impossible. The low C2 and CN production rates may be understood as consequences of Yanaka (1 988r) being a new comet in combination with the small central area of coma observed. The surface of new comets resulting from cosmic-ray pro cessing in the Oort cloud gives rise to dust which is relatively nonfr agile and which remains relatively large and cool within the limits of a small diaphragm making the comet appear to be dust poor. This dust yields smaller abundances of carbon-rich species by evaporation than c ustomary for the smaller and hotter fragmented particles further out i n the coma.