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Dusty Rings in our Solar System:
One Ring, Two Ring
Red Ring Blue Ring
Imke de Pater
UC BerkeleyHammel, Gibbard,
Showalter, ----
Outline:
1. Relation Rings and Planet Formation
2. Formation of Dusty Rings: Jupiter
3. Saturn’s Dusty Rings: E and G
4. Uranus: One Ring Two Ring
Red Ring Blue Ring
prospects for Ring Plane Crossing
Young stars, e.g. T
Tauri stars, are
surrounded by a disk
of material, in which
planets form
Physical processes
in such disks are
similar to those in
rings (clumping,
gaps, waves, ------)
Planetary Rings: So What?
Saturn in 1610: Moons that did not move ---
Galileo
Saturn in 1612: but yet had disappeared ----
Galileo
Saturn in 1616: 4 years later -- handles---
Galileo
Saturn’s appearances
remained puzzling until --
Saturn: Huygens’ sketches in 1655: rings!
HST heritage images
Earth to scale
Infrared Image of Jupiter’s Ring
Jupiter’s rings, observed at 2.3 µm with the Keck telescope.
De Pater et al. 1999
Optical Observation of Jupiter’s Rings
Jovian ring as imaged by Galileo: main ring and
halo in forward scattered light in the visible
Ockert-bell et al. 1999
Galileo: Visible
light, forward
scattered. Note
bright bottom/top
Keck: Infrared
reflected light;
backscattered
Gossamer Rings:
Keck
Burns et al. 1999
Each of the rings is bounded by a satellite ! ring
must somehow be related to satellite.
Production of Ring Particles
Thomas Jefferson on a fall inThomas Jefferson on a fall in
Connecticut (1807):Connecticut (1807):
““It is easier to believe that YankeeIt is easier to believe that Yankee
professors would lie than that stonesprofessors would lie than that stones
would fall from heavenwould fall from heaven””
Production of Ring Particles
Each of the rings is bounded by a satellite ! ring must
somehow be related to satellite.
Meteorites hit moon !
craters. Bedrock is
broken up.
Micrometeorites impact
the moon continuously !
pulverize the bedrock !
Regolith
Production of Ring Particles
Each of the rings is bounded by a satellite ! ring must
somehow be related to satellite.
Meteorites hit moon !
craters. Bedrock is
broken up.
Micrometeorites impact
the moon continuously !
pulverize the bedrock !
Regolith
Upon impact, most material falls back to surface (gravity!).
But for small moons, a fraction escapes, and goes in orbit
around the planet ! Ring!
LorentzResonances
Radial scan through Jupiter’s Main Ring
De Pater et al. 1999
Gossamer Rings
Reproduced quite
well by models of
inward migrating
dust, produced via
meteorite impacts
on moons.
Burns et al. 1999
2.2 µm, Keckobservations
Verbanac et al., 2005
Saturns dusty Rings
Sunlight scattered off Saturn’s Rings
2.2 µm, Keck observations
Verbanac et al., 2005
Saturns dusty rings
De Pater et al. 2004
VIF: 8000 km
VIF: 30,000 km
Radial Profile through Rings
De Pater et al. 2004
Keck, IR
HST, visible
Nicholson et al 1996
G ring is red !
`normal’ dusty
ring
De Pater et al. 2004
E ring is blue !
narrow size
distribution
centered near1 µm radius
De Pater et al. 2004
Moon Enceladus orbits Saturn inside the E ring
Enceladus imaged by Cassini
Enceladus imaged by Cassini
E ring imaged by Cassini --- puzzles continue
Conclusions so far:
• Rings bright in forward scattered light: micron-sizedmaterial. Jupiter’s ring, Saturn’s E ring
• Rings may result from micrometeorite impacts
moons and/or parent material in similar orbits
•Jupiter’s rings and Saturn’s G ring: red
• Saturn’s E ring: Blue --> narrow size distribution withR ~ 1 µm Enceladus geysers/cryovolcanism main
source.
• Tethys secondary source material
Discovery of Uranus’ RingsUranus Rings
Keck Observes Uranus Dusty Rings
AO on
2.2 µm 1.6 µm
off on
Monitoring Uranus with Keck Adaptive Optics
at 2.2 µm, while the rings are closing up. In the
summer 2007 the rings will be edge-on.
De Pater et al. 2006a
Uranus October 2003
Uranus July 2004
Voyager ring 1986U2R at !=900
De Pater et al. 2006a
N-S profiles through rings in July 2004
" 6 5 4 # $ % & ' (
De Pater et al. 2006a
De Pater et al. 2006a
Dusty rings change location, intensity ——in Uranus rings as well as Saturn’s D ring
HST Discovers Uranus
Outer Ring System
Uranus Outer RingsHubble Space telescope ACS
NASA/ESA, M. Showalter (SETI)
New Ring
R/2003 U2
Main Rings
Keck observed U2
in the infrared
De Pater et al. 2006bShowalter and Lissauer2006
HST KECK
ng
2005
De Pater et al. 2006bShowalter and Lissauer2006
Comparison ofRings:
Uranus’ ring R1
Saturn’s G ring with
E ring
R1
G ring
R2
Saturn’s E ring
Uranus’ ring R2
De Pater et al. 2006b
Comparison OuterRing Systems of
Saturn andUranus
Enceladus
Mab
De Pater et al. 2006b
Last crossing: 1965; Next crossing: 2049
Showalter, 2006
CONCLUSIONS Uranus’ ring system
• While rings close up: detection of dusty "-ring
• Dust layers within main rings changed location, and
relative I/F since Voyager flyby
• Outer ring system: like Saturn’s E and G rings
2007: Ring plane crossing:
• details outer ring system
• vertical extent rings
• observe dark side ( ring
Discovery of Neptune’s Rings
Neptune’s ring: discovered via star occultation.
But star light dimmed at only one side!
Neptune’s Ring System
Voyager ring arcs 1989
Neptune rings imaged with Keck
De Pater et al 2005
De Pater et al 2005