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JUPITER'S RING: 1997 and 2002-2003 RPX
Keck images of the Jovian ring at a wavelength of 2.3 micrometer. The ring is visible in reflected sunlight. These observations were taken with the Keck telescope during the planet's ring plane crossing (RPX) 2002-2003, so the rings appear "edge-on". Panels (a) and (b) show images obtained on UT 19 Dec. 2002 and 22 Jan. 2003, with the combined image in panel (c). Panel (d) shows an adaptive optics (AO) image from 26 Jan. 2003. The dashed white line indicates a change in color scale from the main ring to the gossamer rings. The main ring is visible in red-yellow; the halo in green-blue; the gossamer Amalthea ring in light-blue and the gossamer Thebe ring in dark-blue. (Ref. de Pater, I., M. Showalter, and B. Macintosh, 2008. Structure of the Jovian Ring from Keck Observations during RPX 2002-2003. Icarus, 195, 348-360.)
Onion-peeled images from the data in the figure above. The middle row (b) shows the onion-peeled result of the conventional image from panel c above. Panel (c) shows the same image, with a color scale that emphasizes the gossamer rings. The top panel (a) shows the radial distribution as derived from the AO image in panel d of the figure above. (Ref. de Pater, I., M. Showalter, and B. Macintosh, 2008. Structure of the Jovian Ring from Keck Observations during RPX 2002-2003. Icarus, 195, 348-360.)
Jupiter's gosamer rings: Comparison of the Keck observations with a Galileo image and a model from M. Showalter. These data show that the rings are formed from meteorite impacts on Amalthea and Thebe. (see Burns, J.A., D.P. Hamilton, M.R. Showalter, P.D. Nicholson, I. de Pater, and P.C. Thomas, 1999. The formation of Jupiter's faint rings. Science, vol. 284}, pp. 1146-1150.).
Although the paper of de Pater et al. 2008 is focused on Keck
observations of the rings, a quite novel aspect of this paper is that
we were able to combine these measurement with information extracted
from modeling efforts of Jupiter's synchrotron radiation (e.g., de
Pater, I., M. Schulz, and S.H. Brecht, 1997. Synchrotron evidence for
Amalthea's influence on Jupiter's electron radiation belt,
J. Geoph. Res., 102, No. A10, 22,043 - 22,064, and references
therein). With Keck we observed the rings in reflected sunlight at a
wavelength of 2.2 micron. By combining these data with radio
observations, we derived information on both the micron-sized dust
(from the Keck data) and the larger (> cm-sized) particles (from the
radio data) in Jupiter's main ring. The latter particles make up (in
part) the parent bodies from which the rings evolve. About 15% of the
main ring's optical depth is provided by reddish bodies with radii
over 5~cm; the rest is attributed to micron-sized dust, and grains
tens to hundreds of microns in size. The inward extension of the rings
consists of micron-sized dust, which probably migrates inward under
Poynting-Robertson drag. The inner limit of this extension falls near
the 3:2 Lorentz resonance, and coincides with the outer limit of the
halo. In Showalter et al. 2008 (Showalter, M.R., I. de Pater,
G. Verbanac, D.P. Hamilton, and J.A. Burns. 2008. Properties and
dynamics of Jupiter's gossamer rings from Galileo, Voyager, Hubble and
Keck images. Icarus, 195, 361-377), we present a comprehensive study of Jupiter's
gossamer rings based on images from Voyager, Galileo, HST and Keck. We
compare our results to the simple dynamical model of Burns et
al. (Figure above) in which dust is ejected from Amalthea and Thebe and
then evolves inward under Poynting-Robertson drag. The ring follows
many predictions of the model rather well, including a linear
reduction in thickness with decreasing radius. However, most ring
material appears to be concentrated just interior to the orbits of the
two moons, rather than being the broad sheets of material as
predicted.