UKIRT Spectral Images of Fragment C Impact
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Fragment C Impact Seen at UKIRT
The following message was sent to the Jupiter/comet news center at the
University of Maryland. The image above combines an observation taken before
(top) and about fifteen minutes after (bottom) impact. Both spectral images were
obtained with the 1.1" wide slit aligned along 45 degrees south latitude.
Spectral line graphs of these images can be found here.
CGS4 (with echelle at about 20 km/s resolution) on UKIRT detected dramatic
changes in the spectrum near 3.5um at the location where the C fragment struck
Jupiter. In addition to a bright continuum (where there previously was
essentially none), the relative strengths of pre-existing emission lines of H3+
changed and many new lines appeared, very few of which are identified by us at
present. In particular, at the wavelength of a previously undetectable "hot
band" transition of H3+, a bright line appeared whose strength surpassed that of
all other pre-existing H3+ lines. A second line, unidentified at present,
succeeded in saturating its central pixel in a ten second exposure. Some of the
lines seem considerably (Doppler) broadened, but, due to the high density of
spectral features, confirmation will have to wait until after the observers get
some sleep. The emission faded with a 1/e time of roughly 15 minutes.
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