Io Plasma Torus

From August 2002 to July 2004, I was a National Research Council Postdoc in the Laboratory for Astronomy and Solar Physics (LASP) at NASA/GSFC for Ron Oliversen. The general topic of my study was the Io plasma torus, a body of hot gas that is entrained in Jupiter's magnetic field. The plasma comes at least indirectly from Io's volcanoes. The plasma, which is visible in ionic emission, such as S+, pictured above (Woodward et al), also interacts with Io, in particular its atmosphere. A team from the University of Wisconsin and NASA/GSFC, led by Frank Scherb found that oxygen emission ([OI] 6300 Å) from Io was detectable from the ground (Scherb & Smyth 1993). This led to more than a decade's worth of observations using the stellar spectrograph at the McMath-Pierce solar telescope facility; more than 3000 spectra have been recorded. The ~1000 spectra that have been fully reduced show the [O I] line varies in intensity over all time scales (Oliversen et al. 2001). Oliversen et al. began the task of untangling the various effects in the time signature by using a detailed model of the torus "average conditions."

Jeffrey P. Morgenthaler 2008-12-16