The effect of the impact of comet Shoemaker Levy‐9 on Jupiter's aurorae

Abstract

Abstract. We present infrared spectra and images of the jovian aurorae taken at wavelengths sensitive to the H3 + molecular ion during the period around the im-

Jovian magnetospheric and auroral effects of the SL9 impacts

“…A similar property of longitudinal variation is shared by the UV and infrared emissions from the jovian aurora (Herbert et al 1987;Livengood et al 1990;Miller et al 1995). The imaging observations of H j auroral emission in the infrared (Connerney et al 1993) 1 COMET IMPACT POINT FIGURE 2.…”

“…Several programs of infrared observations during the comet impact week were planned. Of major importance in the study of jovian auroral activities are (a) the imaging and spectroscopic measurements at 3.53 /im of the H^ emission by the University College London group (Miller et al 1995) (Schulz et al 1995), and (c) the CASPIR on the ANU 2.3 m telescope at the Siding Spring Observatory, Australia (McGregor et al 1995).…”

“…Sudden unusual variations of the auroral emission were reported by all three groups. For example, the UKIRT and IRTF observations by Miller et al (1995) showed that between 25 and 27 July the N/S ratio was seen to increase to ss 6-10 before returning to the average value of about 3. This change was caused in part by the enhancement of the northern emission and in part by a suppression of the southern one.…”

“…This change was caused in part by the enhancement of the northern emission and in part by a suppression of the southern one. Another important result from Miller et al (1995) concerns the fact that very strong longitudinal variations were also found. The northern emission reached the highest intensity at Xuj between 90° and 270° while the southern emission generally leveled off to values below the pre-impact intensities.…”

“…The northern emission reached the highest intensity at Xuj between 90° and 270° while the southern emission generally leveled off to values below the pre-impact intensities. To explain this remarkable north-south asymmetry, Miller et al (1995) suggested that it could be due to the reduction of the ionospheric Pedersen conductivity in the southern auroral zone because of the injection of a large amount of H2O and CO molecules and dust of cometary origin (Cravens 1994). This would effectively shortcircuit the field-aligned current flow between the equatorial plasma sheet and the southern hemisphere but would double the electric current going into the northern part and hence the temporal variation of the N/S ratio of the H3" auroral emissions.…”