Evidence for auroral influence on Jupiter’s nitrogen and oxygen chemistry revealed by ALMA

The localized delivery of new long-lived species to Jupiter’s stratosphere by comet Shoemaker–Levy 9 in 1994 opened a window to constrain Jovian chemistry and dynamics by monitoring the evolution of their vertical and horizontal distributions. However, the spatial distributions of CO and HCN, two of these long-lived species, had never been jointly observed at high latitudinal resolution. Atacama large millimeter/submillimeter array observations of HCN and CO in March 2017 show that CO was meridionally uniform and restricted to pressures lower than 3 ± 1 mbar. HCN shared a similar vertical distribution in the low- to mid-latitudes, but was depleted at pressures between $${2}_{-1}^{+2}$$ and $${0.04}_{-0.03}^{+0.07}$$ mbar in the aurora and surrounding regions, resulting in a drop by two orders of magnitude in column density. We propose that heterogeneous chemistry bonds HCN on large aurora-produced aerosols at these pressures in the Jovian auroral regions causing the observed depletion. Trace gases CO and HCN are detected by ALMA in various locations of Jupiter’s disc. Contrary to CO, HCN is depleted in the auroral regions, indicative of the action of heterogeneous chemistry that bonds HCN to organic aerosol particles produced in the aurorae.