orbital evolution of the galilean satellites
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Orbital Evolution of the Galilean Satellites. Kaveh Pahlevan Doug Hamilton Dept. of Astronomy University of Maryland College Park, MD 20742. Why study the Galilean Satellites?. - PowerPoint PPT PresentationTRANSCRIPT
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Orbital Evolution of theGalilean SatellitesKaveh PahlevanDoug Hamilton
Dept. of Astronomy University of MarylandCollege Park, MD 20742
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Why study the Galilean Satellites? Diverse & interesting planetary bodies
- Local analogue to planetary systems
- Can give insight to general formation processes.
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Observations: I. Physical Properties
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Observations: II. Orbital Properties
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Resonances: I.When a small perturbation adds coherently over time, the system is in resonance.A mean motion resonance can occur when the ratio of two orbital frequencies is a small integer.
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Resonances: II.Splitting When satellites orbit an oblate planet, the components of a resonance split into several closely spaced resonances.
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The Laplace ResonanceTidal Origin: The outward migration of the satellites due to tides from Jupiter collected the inner three satellites into the resonance.
Primordial Origin: Inward migration during the formation era collected the satellites into the resonance.
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Resonances: I.When a small perturbation adds coherently over time, the system is in resonance.A mean motion resonance can occur when the ratio of two orbital frequencies is a small integer.
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The 2:1ecc/4:2inc Resonance Rate: 10-6 RJ/dayRate: 10-11 RJ/day
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The 2:1/4:2 Resonance SummaryEccentricity KicksInclination Kicks
Chart1
0.030.01
0.040.02
0.040.02
0.040.02
0.040.02
0.040.02
0.040.02
0.040.02
0.040.02
0.040.02
Ganymede
Callisto
Log [Rate]
Eccentricity
Eccentricity Kick vs. Drag Rate
Sheet1
Rate (RJ/day)Log[Rate]eGeCiGiC
1 x 10-440.030.01----
1 x 10-550.040.02----
1 x 10-660.040.02----
1 x 10-660.040.02----
1 x 10-660.040.02----
1 x 10-770.040.021 x 10-6--
1 x 10-880.040.021 x 10-6--
1 x 10-990.040.02-1 x 10-6--
1 x 10-10100.040.023 x 10-51 x 10-5
1 x 10-11110.040.022 x 10-41 x 10-4
Sheet1
00
00
00
00
00
00
00
00
00
00
Ganymede
Callisto
Log [Rate]
Eccentricity
Eccentricity Kick vs. Drag Rate
Sheet2
Sheet3
Chart4
-8-8
-8-8
-8-8
-8-8
-8-8
-6-8
-6-8
-8-8
-4.5-5
-3.7-4
Ganymede
Callisto
Log [Rate]
Log[Inclination]
Inclination Kick vs. Drag Rate
Sheet1
Log[Rate]log(ig)log(ic)
4-8-8----
5-8-8----
6-8-8----
6-8-8----
6-8-8----
7-6-8--
8-6-8--
9-8-80--
10-4.5-5
11-3.7-4
16.588461
16.5886372-1-1000
16.5893492-10-100
Sheet1
Ganymede
Callisto
Log [Rate]
Log[Inclination]
Inclination Kick vs. Drag Rate
Sheet2
Sheet3
MBD00292CB5.xls
Chart1
0.030.01
0.040.02
0.040.02
0.040.02
0.040.02
0.040.02
0.040.02
0.040.02
0.040.02
0.040.02
Ganymede
Callisto
Log [Rate]
Eccentricity
Eccentricity Kick vs. Drag Rate
Sheet1
Rate (RJ/day)Log[Rate]eGeCiGiC
1 x 10-440.030.01----
1 x 10-550.040.02----
1 x 10-660.040.02----
1 x 10-660.040.02----
1 x 10-660.040.02----
1 x 10-770.040.021 x 10-6--
1 x 10-880.040.021 x 10-6--
1 x 10-990.040.02-1 x 10-6--
1 x 10-10100.040.023 x 10-51 x 10-5
1 x 10-11110.040.022 x 10-41 x 10-4
Sheet1
00
00
00
00
00
00
00
00
00
00
Ganymede
Callisto
Log [Rate]
Eccentricity
Eccentricity Kick vs. Drag Rate
Sheet2
Sheet3
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Resonances: I.When a small perturbation adds coherently over time, the system is in resonance.A mean motion resonance can occur when the ratio of two orbital frequencies is a small integer.
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The 3:1 Resonance at 10-9 RJ/day
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The 3:1 Resonance at 10-12 RJ/day
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The 3:1 Resonance - SummaryIf the Laplace resonance is primordial, Ganymede must have passed through the 3:1 resonance with Callisto.Simulations: such a passage typically leads to inclinations of a degree or more.No known process can damp inclinations Argues for a tidal origin for the assembly of the Galilean satellites into the Laplace resonance.
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Resonances: I.When a small perturbation adds coherently over time, the system is in resonance.A mean motion resonance can occur when the ratio of two orbital frequencies is a small integer.
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The 5:2 Resonance at 10-11 RJ/day
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The 5:2 Resonance at 10-12 RJ/day
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So, what have we learned?2:1 resonance can deliver an early heat pulse to both satellites, but preferentially heats Ganymede.
5:2 resonance third order resonance much more difficult to study. Our preliminary results suggest that the present day inclinations might be explained by passage through this resonance.3:1 resonance probably did not occur. If we can confirm this result, then the primordial assembly of the satellites into resonance did not take place.
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Man with all his noble qualities . . . with his god-like intellect which has penetrated into the movements and constitution of the solar systemwith all these exalted powersman still bears in his bodily frame the indelible stamp of his lowly origin.
Charles Darwin, The Descent of Man, Closing words of book.