ALMA spectral imaging of SL9 species in Jupiter’s stratosphere

Abstract

In July 1994, the Shoemaker-Levy 9 comet (SL9) spectacularly impacted Jupiter near 44°S. On the long term, Jupiter was left with a variety of new species in its stratosphere, including CO, HCN, CS, H2O, and CO2. These species can be used as tracers for Jupiter’s stratospheric chemistry and dynamics. Their distributions have been monitored, although with strong limitations in terms of spatial resolution in most cases. We mapped the spectral emissions of CO and HCN (at 345 and 354 GHz, resp.) in Jupiter with ALMA in March 2017. We have successfully performed the first mosaic of Jupiter to cover the entire planet. We have recorded the data with a very high spectral resolution (up to 61 kHz) and at an unprecedented angular resolution of 1.1”, which translates into a meridional resolution of 3° at the equator and 7° at 70°S. The lines are detected at the planetary limb with a high signal-to-noise ratio. The emission distributions and line shapes at the limb indicate strong meridional variability for CO and HCN, quite different from one another. In this paper, we will present our observations and preliminary interpretation of the observed distributions