Paper: astro-ph/0505409
Date: Thu, 19 May 2005 14:13:24 GMT (698kb)

Title: Discovery of Oxygen Kalpha X-ray Emission from the Rings of Saturn

Authors: Anil Bhardwaj, Ronald F. Elsner, J. Hunter Waite, Jr., G. Randall
Gladstone, Thomas E. Cravens, and Peter G. Ford
Comments: 14 pages, 5 figures Astrophys. J Lett., in press
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Using the Advanced CCD Imaging Spectrometer (ACIS), the Chandra X-ray
Observatory (CXO) observed the Saturnian system for one rotation of the planet
(~37 ks) on 20 January, 2004, and again on 26-27 January, 2004. In this letter
we report the detection of X-ray emission from the rings of Saturn. The X-ray
spectrum from the rings is dominated by emission in a narrow (~130 eV wide)
energy band centered on the atomic oxygen K-alpha fluorescence line at 0.53
keV. The X-ray power emitted from the rings in the 0.49-0.62 keV band is 84 MW,
which is about one-third of that emitted from Saturn disk in the photon energy
range 0.24-2.0 keV. Our analysis also finds a clear detection of X-ray emission
from the rings in the 0.49-0.62 keV band in an earlier (14-15 April, 2003)
Chandra ACIS observation of Saturn. Fluorescent scattering of solar X-rays from
oxygen atoms in the H2O icy ring material is the likely source mechanism for
ring X-rays, consistent with the scenario of solar photo-production of a
tenuous ring oxygen atmosphere and ionosphere recently discovered by Cassini.

\\ ( http://arXiv.org/abs/astro-ph/0505409 , 698kb)