Issue |
A&A
Volume 418, Number 1, April IV 2004
|
|
---|---|---|
Page(s) | 337 - 345 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361:20035736 | |
Published online | 02 April 2004 |
X-ray emission from Saturn
1
Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
2
Chandra X-ray Center, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
3
Max-Planck-Institut für extraterrestrische Physik (MPE), Postfach 1312, 85741 Garching, Germany
Corresponding author: J.-U. Ness, jness@hs.uni-hamburg.de
Received:
24
November
2003
Accepted:
7
January
2004
We report the first unambiguous detection of X-ray emission originating from
Saturn with a Chandra observation, duration 65.5 ks with ACIS-S3. Beyond the
pure detection we analyze the spatial distribution of X-rays on the planetary
surface, the light curve, and some spectral properties. The detection is based
on 162 cts extracted from the ACIS-S3 chip within the optical disk of
Saturn. We found no evidence for smaller or larger angular extent. The
expected background level is 56 cts, i.e., the count rate is
cts/s. The extracted photons are rather
concentrated towards the equator of the apparent disk, while both polar caps
have a relative photon deficit. The inclination angle of Saturn during the
observation was ~
, so that the northern hemisphere was not
visible during the complete observation. In addition, it was occulted
by the ring system. We found a small but significant photon excess
at one edge of the ring system. The light curve shows a small dip twice at
identical phases, but rotational modulation cannot be claimed at a significant
level. Spectral modeling results in a number of statistically, but not
necessarily physically, acceptable models. The X-ray flux level we calculate
from the best-fit spectral models is ~
(in the energy
interval 0.1–2 keV), which corresponds to an X-ray luminosity of ~
. A combination of scatter
processes of solar X-rays require a relatively high albedo favoring internal
processes, but a definitive explanation remains an open issue.
Key words: planets and satellites: general / planets and satellites: individual: Saturn / X-rays: general
© ESO, 2004
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