The F Ring Strands
Overview & My milestone in understanding
Nicole Albers
PIA 07522
The F ring “temperature” at different epochs
Nicole Albers
UVIS Team Meeting, Berlin, 8th -10th June 2009
Three Feature Categories:
Core usually determined as the densest part
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Strands material apparently organized into bands
inner and outer ones
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Multiple new, previously unseen strand with
characteristics typical for the core as seen
HSP
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by the
“Easily” distinguished from another by location and morphology
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But morphology is not distinct but rather show continuous
transition suggest common nature of strands and core
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Morphology of F ring features
Possible misidentifications? e.g. Del Per R36, Zet Cen R62, The Hya 70 in
(list is uncomplete and in progress)
Detections relative to the F ring orbit model
PIA 07716
The Kinematic Spiral (1)
Charnoz et al. (2005)
Orbit model based on Cassini UVIS HSP and Voyager PPS and RSS:
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Captures the mean motion of the core well (no glitches in this panorama)
Rectifies the strands and truly reveals their linear appearance
Charnoz et al. (2005)
The Kinematic Spiral (2)
Charnoz et al. (2005)
The Kinematic Spiral (3)
The simplest of all spirals
(after 1 year ~ 547 orbits)
The simplest of all spirals
(Creation at Spiral Epoch)
The simplest of all spirals
(after 180 days ~ 270 orbits)
The simplest of all spirals
(after 4 years)
The simplest of all spirals
(after 5 years)
Spiral Slope Variation in Time (spiral flattens as it winds up)
Spiral Slope Variation in Longitdue (relative eccentricity)
It's extremely hard not to create a spiral! (but non-zero de/da)
Judging by these strands should:
~6 years until they are within 100km of the core
but with high relative eccentricities leading to
strand core interactions
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Predicted ~190days for wrapping around seem ok
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Material spreads along the azimuth continuously
making the strand fainter in time
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Underlying impression of an average orbit
consistent with orbit model fits that always showed
a sinusoidal residual pattern
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Origin in the core only coincides a short time with
actual core intersection of spiral
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Spiral are a naturally optical illusion pattern
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Where's the spiral here? (work in progress)
Not simply shifting left and right to match a straight line
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First simple analytic model does not compare to a
straight line as seen in imaging/simulations
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Possible misidentification owing to discontinuous core
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Multiple detection of the same feature in one occultation
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