Far-ultraviolet imaging spectroscopy of Io's atmosphere with HST/STIS.
Well-resolved far-ultraviolet spectroscopic images of O I, S I, and previously undetected H ILyman-alpha emission from Io were obtained with the Hubble space telescope imaging spectrograph (STIS). Detected O I and S I lines (1250 to 1500 angstroms) have bright equatorial spots (up to 2.5 kilorayleighs) that shift position with jovian magnetic field orientation; limb glow that is brighter on the hemisphere facing the jovian magnetic equator; and faint diffuse emission extending to approximately 20 Io radii. All O I and S I features brightened by approximately 50 percent in the last two images, concurrently with a ground-based observation of increased iogenic [O I] 6300-angstrom emission. The H ILyman-alpha emission, consisting of a small, approximately 2-kilorayleigh patch near each pole, has a different morphology and time variation.
Roesler
F L
FL
Physics Department, University of Wisconsin, 1150 University Avenue, Madison, WI 53706, USA.
Moos
H W
HW
Oliversen
R J
RJ
Woodward
R C
RC
Retherford
K D
KD
Scherb
F
F
McGrath
M A
MA
Smyth
W H
WH
Feldman
P D
PD
Strobel
D F
DF
D001272:Atmosphere; D005118:Extraterrestrial Environment; D006859:Hydrogen; D018538:Jupiter; D008280:Magnetics; D010100:Oxygen; D013056:Spectrophotometry, Ultraviolet; D013455:Sulfur
D013455:Sulfur; D006859:Hydrogen; D010100:Oxygen