Knowledge Bank

The recent detection of the $H+3\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$ molecular ion in the Jovian auroral $region1,2,3$ via its $2\mu m2\nu 2\leftarrow 0$ overtone band is the first instance that this hydrogenic species, which is thought to be basic to the production of many complex molecules in the interstellar medium, has been detected by astronomical observation. In this paper we report our detection of 10 lines belonging to the $4\mu m$ fundamental $\nu 2$ band of $H3\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$ in emission in the northern and southern polar ionosphere of Jupiter. The previously observed $2\mu m$ overtone band emission was absent as were lines of other hot bands of $H3+$ and the $2\mu m$ lines of $H2$ indicating a drastic temporal dependence of physical conditions in Jovian $ionosphere.4$