On the dynamics of the jovian ionosphere and thermosphere II.: The measurement of H3+ vibrational temperature, column density, and total emission

We present the first reported measurements of the intensity of a hotband transition for the H-3(+) molecular ion in the northern auroral/polar region of Jupiter. This transition is identified as the R(3, 4(+)) line of the (2v(2) (l = 0) --> v(2)) hotband, with a wavelength of 3.94895 gm. This is the first time such a transition has been measured outside the laboratory, and the wavelength as measured on Jupiter is within the experimental accuracy of the lab measurement. This detection makes it possible to investigate H-3(+) transitions that simultaneously originate from different vibrational levels. We use the intensity ratio between this line and the Q(1, 0(-)) fundamental transition to derive effective vibrational temperatures, column densities, and total emission parameters as a function of position across the auroral/polar region. Effective temperatures range from similar to900 to similar to1250 K; an increase in average temperature during our observing run of similar to100 K is noted. The derived temperatures are toward the high end or in excess of the auroral temperature range that has been reported in the literature to date. The relationship among emission intensity, temperature, and density is shown to be complex. This may reflect the nonthermalization of the vibrational levels at the gas densities prevailing in the jovian thermosphere. An alternative analysis allowing for this effect is presented. But this approach requires thermospheric temperatures to be similar to1500 K at the level that the majority of H-3(+) is being produced, higher than has previously been proposed. (C) 2002 Elsevier Science (USA).