Astronomy and Astrophysics – Astrophysics – Earth and Planetary Astrophysics
Scientific paper
2010-08-10
Geophys. Res. Lett. 37, L14205 (2010)
Astronomy and Astrophysics
Astrophysics
Earth and Planetary Astrophysics
12 pages, 6 figures; Published in GRL
Scientific paper
10.1029/2010GL043663.
We have conducted an intensive search for any material that may orbit Rhea, using images obtained by the Cassini ISS narrow-angle camera. We find no evidence for any such material, contradicting an earlier and surprising inference that Rhea, the second-largest moon of Saturn, possesses a system of narrow rings embedded in a broad circum-satellite disk or cloud (Jones et al. 2008, Science). If one accepts the calculations of the previous authors, our results would require any narrow rings around Rhea to be composed of objects no smaller than 10 meters in radius, in order to be massive enough to account for the observed charged-particle absorptions but diffuse enough to evade detection in our images. Such a particle-size distribution is unrealistic given that erosion processes will break down 10-meter objects to smaller sizes, which would then have been seen in our images. Furthermore, Jones et al. (2008) assumed that the absorption of electrons by hypothetical circum-Rhea particles is proportional to the volume of the particles, even when they are much larger than the electron penetration depth (van Allen 1983, 1987, JGR). If we assume instead that large particles can only absorb electrons efficiently near their surfaces, then our results rule out any solid material orbiting Rhea as the explanation for the absorptions detected by Jones et al. (2008), regardless of particle size, by a margin of four (for narrow rings) or two (for a broad diffuse cloud) orders of magnitude. We conclude that the anomalous electron absorptions reported by Jones et al. (2008) are the signature of a new and hitherto unknown magnetospheric process.
Burns Joseph A.
Cuzzi Jeffrey N.
Hedman Matthew M.
Tiscareno Matthew S.
No associations
LandOfFree
Cassini imaging search rules out rings around Rhea does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Cassini imaging search rules out rings around Rhea, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cassini imaging search rules out rings around Rhea will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-584460