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Session 70 - Planetary Systems Near & Far.
Display session, Friday, January 09
Exhibit Hall,
Observations of Io FUV emission lines were obtained with the Space Telescope Imaging Spectrograph on 1997 October 14. The observations were made in a time-tagged, G140L mode using a 2'' wide by 52'' long slit. The spectral dispersion of 0.292\,Åpixel and spatial resolution of 0.0122''/pixel provide good isolation of the dominant spatial features associated with O\,I and S\,I emission near Io. These features are similar in appearance to undispersed images of Io in eclipse obtained from Galileo and by Trauger using a 6300Å\ filter on WFPC2; prominent emissions are seen off the limb in the equatorial region, and extend more faintly around the entire limb of Io. Neutral emission is also evident along the slit, decreasing with distance to several Io radii. Torus emission lines of S\,II, S\,III, and S\,IV also appear in the field. Emission features of Lyman-\alpha associated with Io are detected behind the strong geocoronal Lyman-\alpha foreground emission.
