INFRARED-SPECTRA OF THE R-IMPACT OF COMET SHOEMAKER-LEVY-9

We report a series of 2.2- to 2.4-mu m spectra of the R impact of Come t Shoemaker-Levy 9 obtained with the UKIRT telescope. Spectra were rec orded at approximately 1- to 2-min intervals spanning the impact event . During the rapid rise of the splashback flash, we observed apparent continuum emission, probably from dust, as well as band/line emission from CH4 and possibly other molecules. At 3 to 4 min into the splashba ck, the 2-0 bandhead of CO became prominent. CO excitation temperature s were greater than 2000 K near the peak of the splashback emission. A s the splashback emission declined, the CO temperature continued to ri se, as predicted by some models of the splashback. LTE models of the s pectra, incorporating CH4 and CO, require on the order of 10(11) g of hot CO. This is a small fraction of the total observed by radio techni ques sensitive to cold CO. (C) 1997 Academic Press.