Heterodyne millimeter observations of Jupiter performed after the collision of comet SL9 with the planet

 
Figure 2: CS J=5-4 (244.9 GHz) observed in absorption on Aug. 12, 1994.

The IRAM 30m has continued its monitoring of Jupiter at several fragment locations a long time after the last impacts, using the same observing procedure. We have performed new detections of CO and CS lines, unambiguously observed in absorption at the same frequencies. We have checked whether these features might be artefact effects in the observational procedure and conclude they are not.

During three months following the SL9 crash a lot of observations have thus been carried out and the significant aspects of the recorded spectra have been analysed in more detail, (Marten et al., B.A.A.S., 1994, 26, DPS Meeting, reference above). The line widths of absorption lines are about the same order than those of emission features indicating that the origin of the absorbers is purely stratospheric.

Recently, a program of observations of Jupiter in the HCN lines has been conducted with the JCMT in Hawaii. The similarity of measured features gives us complementary information for interpreting the CO and CS lines. It is worthwhile to note that both kinds of observations are effectively unique and of major interest. The Meudon scientists are, moreover, involved in the two sets of observations.

Since the spectral signatures of carbon compounds did not disappear rapidly, there is evidence of the presence of a cold molecular atmospheric layer resulting from the comet impacts. We have now to investigate the conditions of formation and destruction of the new species created in the stratosphere of Jupiter.

We are indebted to M. Grewing and M. Guélin for providing this unique opportunity of monitoring Jupiter during extra time periods of observations with the IRAM 30m Telescope.