Discovery of soft X-ray emission from Io, Europa, and the Io Plasma Torus

Elsner, Ronald F. ; Gladstone, G. Randall ; Waite, J. Hunter ; Crary, Frank J. ; Howell, Robert R. ; Johnson, Robert E. ; Ford, Peter G. ; Metzger, Albert E. ; Hurley, Kevin C. ; Feigelson, Eric D. ; Garmire, Gordon P. ; Bhardwaj, Anil ; Grodent, Denis C. ; Majeed, Tariq ; Tennant, Allyn F. ; Weisskopf, Martin C. (2002) Discovery of soft X-ray emission from Io, Europa, and the Io Plasma Torus Astrophysical Journal, 572 (2). pp. 1077-1082. ISSN 0004-637X

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We report the discovery of soft (0.25-2 keV) X-ray emission from the Galilean satellites Io and Europa, probably Ganymede, and from the Io Plasma Torus (IPT). Bombardment by energetic (greater than 10 keV) H, O, and S ions from the region of the IPT seems to be the likely source of the X-ray emission from the Galilean satellites. According to our estimates, fluorescent X-ray emission excited by solar X-rays, even during flares from the active Sun, charge-exchange processes, previously invoked to explain Jupiter's X-ray aurora and cometary X-ray emission, and ion stripping by dust grains fail to account for the observed emission. On the other hand, bremsstrahlung emission of soft X-rays from nonthermal electrons in the few hundred to few thousand eV range may account for a substantial fraction of the observed X-ray flux from the IPT.

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Deposited On:07 Oct 2010 11:08
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