The estimated temperature of Hessdalen lights is about 5,000 K (4,730 °C; 8,540 °F). At this temperature, the rate coefficients of dissociative recombination will be 10 cm s for the oxygen ions, and 10 cm s for the nitrogen ions. Thus, in the Hessdalen lights plasma, the nitrogen ions will decompose (N 2 + e → N + N*) more rapidly than oxygen ions. Only ionic species are transported by ion acoustic waves. Therefore, oxygen ions will dominate in the ejected green light balls in Hessdalen lights, presenting a negative band of O 2 with electronic transition b Σ g → a Π u after ion-acoustic wave formation.