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Chandra Observations of Jupiter
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High-spatial resolution Chandra x-ray observations demonstrate that most of
Jupiter's northern auroral x-rays come from a hot spot located significantly
poleward of the latitudes connected to the inner magnetosphere. This hot
spot appears fixed in magnetic latitude and longitude and coincides with a
region exhibiting anomalous ultraviolet and infrared emissions.
(The image at right is time-averaged; hence, the emission appears
at all longitudes. Click on the image for an enlargement. Here is a link to the
time-resolved series of images.)
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The hot spot also exhibits approximately 45 minute quasi-periodic
oscillations, a period similar to those reported for high-latitude
radio and energetic electron bursts observed by near-Jupiter spacecraft.
These results invalidate the idea that jovian auroral x-ray emissions
are mainly excited by steady precipitation of energetic heavy ions
from the inner magnetosphere.
Instead, the x-rays appear to result from currently unexplained
processes in the outer magnetosphere that produce highly localized
and highly variable emissions over an extremely wide range of
wavelengths.
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Jupiter's Moons in X-Rays
Chandra observations also reveal for the first time very faint x-ray emission
(about 1-2 MW) from the Galilean moons Io, Europa, and possibly Ganymede (left).
The emission from the moons is almost certainly due
to K-alpha emission from surface atoms (and possibly impacting atoms) excited
by the impact of highly energetic protons, oxygen, and sulfur atoms and ions
from the Torus.
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SZ Effect