Astronomy and Astrophysics – Astronomy
Scientific paper
Apr 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011dda....42.0803n&link_type=abstract
American Astronomical Society, DDA meeting #42, #8.03; Bulletin of the American Astronomical Society, Vol. 43, 2011
Astronomy and Astrophysics
Astronomy
Scientific paper
The outer edge of Saturn's B ring has long been associated with the
2:1 ILR with Mimas (Goldreich & Tremaine 1978). Voyager observations
confirmed this relationship, revealing a 2-lobed radial distortion
with an amplitude of 75 km, rotating with Mimas (Porco
etal. 1984). Cassini imaging data, however, have revealed a more
complex picture, with both forced and free m=2 perturbations as well
as additional m=1 and m=3 components (Spitale & Porco 2010 [SP10]). A
preliminary analysis of Cassini stellar and radio occultation data
suggested that the m=2 perturbation could be modeled as librating
about the expected forced solution (Hedman et al. 2010).
We present here a more complete analysis of the full suite of
occultation data for the B ring edge, including Voyager and
Earth-based observations as well as 140 radio and stellar occultation
data acquired by the Cassini RSS, UVIS and VIMS instruments between
May 2005 and July 2009. Our best-fitting model includes three
distinct perturbations, with 11 free parameters. In agreement with
SP10, we find that the dominant m=2 component actually circulates
relative to Mimas. Due to a near-equality of the forced and free m=2
amplitudes, the overall radial amplitude of the m=2 distortion varies
from a minimum of 4 km to a maximum of 71 km, with a period of 5.42
yr. Superimposed on this oscillating m=2 distortion is a
slowly-precessing m=1 component with an amplitude of 20.6 km and a
rapidly-rotating m=3 component with an amplitude of 14.6 km. The
pattern speeds are consistent with those predicted for "normal modes"
excited just interior to the B ring's edge, as first noted by SP10.
Despite such a complex kinematic model, the post-fit RMS residuals are
10.1 km, or about 10 times the observational errors, suggesting that
significant unmodelled high-frequency radial variations exist.
Colwell Joshua E.
French Richard G.
Hedman Matthew M.
Nicholson Philip D.
No associations
LandOfFree
The Edge of the B Ring 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 The Edge of the B Ring, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Edge of the B Ring will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-763800