title: Io's atmospheric response to eclipse: UV aurorae observations.
abstract: The New Horizons (NH) spacecraft observed Io's aurora in eclipse on four occasions during spring 2007. NH Alice ultraviolet spectroscopy and concurrent Hubble Space Telescope ultraviolet imaging in eclipse investigate the relative contribution of volcanoes to Io's atmosphere and its interaction with Jupiter's magnetosphere. Auroral brightness and morphology variations after eclipse ingress and egress reveal changes in the relative contribution of sublimation and volcanic sources to the atmosphere. Brightnesses viewed at different geometries are best explained by a dramatic difference between the dayside and nightside atmospheric density. Far-ultraviolet aurora morphology reveals the influence of plumes on Io's electrodynamic interaction with Jupiter's magnetosphere. Comparisons to detailed simulations of Io's aurora indicate that volcanoes supply 1 to 3% of the dayside atmosphere.
authors.affiliation: Southwest Research Institute, San Antonio, TX 78228, USA. KRetherford@swri.edu
authors.forename: K D
authors.initials: KD
authors.lastname: Retherford
authors.forename: J R
authors.initials: JR
authors.lastname: Spencer
authors.forename: S A
authors.initials: SA
authors.lastname: Stern
authors.forename: J
authors.initials: J
authors.lastname: Saur
authors.forename: D F
authors.initials: DF
authors.lastname: Strobel
authors.forename: A J
authors.initials: AJ
authors.lastname: Steffl
authors.forename: G R
authors.initials: GR
authors.lastname: Gladstone
authors.forename: H A
authors.initials: HA
authors.lastname: Weaver
authors.forename: A F
authors.initials: AF
authors.lastname: Cheng
authors.forename: J Wm
authors.initials: JW
authors.lastname: Parker
authors.forename: D C
authors.initials: DC
authors.lastname: Slater
authors.forename: M H
authors.initials: MH
authors.lastname: Versteeg
authors.forename: M W
authors.initials: MW
authors.lastname: Davis
authors.forename: F
authors.initials: F
authors.lastname: Bagenal
authors.forename: H B
authors.initials: HB
authors.lastname: Throop
authors.forename: R M C
authors.initials: RM
authors.lastname: Lopes
authors.forename: D C
authors.initials: DC
authors.lastname: Reuter
authors.forename: A
authors.initials: A
authors.lastname: Lunsford
authors.forename: S J
authors.initials: SJ
authors.lastname: Conard
authors.forename: L A
authors.initials: LA
authors.lastname: Young
authors.forename: J M
authors.initials: JM
authors.lastname: Moore