CEDAR: Nightglow Emissions at Solar Maximum

Sri International, Menlo Park CA

Investigators

Abstract

The PIs propose to use astronomical sky spectra to investigate the terrestrial nightglow under solar maximum conditions, and in the declining phase of solar cycle 23. The work is directly relevant to the goal of improving our understanding of solar-terrestrial interactions, as outlined in the phase III agenda of the CEDAR program. From limited data collected in 2000, they have identified most of the Rydberg transitions from atomic oxygen in the visible and near-infrared regions of the spectrum. Except for the lines at 777.4 and 844.6 nm, these emissions have not previously been seen in the nightglow. Of two types of Rydberg transitions, triplets and quintets, the quintets have been little studied even in the laboratory, yet they tend to be the stronger in the sky spectra. The PIs will compare both triplets and quintets against theoretical calculations, with the goals of (1) using the observed intensities as a relative intensity calibration standard and (2) determining variability in the triplets as a consequence of radiation trapping.