dusk - university of washington
TRANSCRIPT
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Dusk
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Io
Dusk
Ganymede
Dawn
Europa
Closure of cororation currents in the auroral zone?
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Pulsating X-ray spot – 45 minute period
Relativistic electrons with 40 minute intensity variations on the dusk side, high latitude
Quasi-periodic explosive magnetic merging process
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During quiet solar activity times, Jupiter a stronger radio source than the Sun
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Jupiter magnetic field strength - “surface” equatorial field = 700000 nT
Jupiter corotation rate - 9.6 hours
Internal plasma source - 1 ton s-1 lost from Io
Processes controlling Jovian magnetosphere
More than 100 known active volcanoes
Torus made of S+, S++, O+, O++
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Io
Dusk
Ganymede
Dawn
Europa
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Multiple Footprint Aurora
Alfven wing
Torus
∇ρ
∇ρ
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MA = 0.3
β = 0.04
Ms > 1 but fast Mach number < 1
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Io has equatorial aurora
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Plasma Density and Flow
Io’s ionosphere is strongly advections dominated
Plasma slowed in Io’s ionosphere, redirected around moon, an thenreaccelerated in the wake (by ~ 6RJ).
Ionosphere has smaller density and smaller scale height on upstream sidemaximum density seen in the flanks ~ 10xenhancement in wake ~ 5x
How is mass supplied to torus? How is it heated/accelerated?
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About 2/3 of iogenic material lost through charge exchange
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Neutral Cloud
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Jet : Electric fields associated with Jupiter’s magnetospheric interaction with Iorip ions out of Io’s collisionally thick atmosphere.
Flow directionin Io frame
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Stream : Leads Io’s oribit and undulates above and below the centrifugal equator. Stream formed by NaX+.
Flow directionin Io frame
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Banana : Low energy neutral cloud generated by sputtering
Flow directionin Io frame
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Closer to Jupiter thanIo, at ~ 5.6 RJ
At the sameradial distanceas Io
Ribbon - tracer for position of max density
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Ribbon
Warm torusCold torus
Ti, ne, ni decreasene, ni, increase at center to cold torus
Ti decreasene increase
Io
Ti peak
Ribbon
ne, ni DecreaseTi, Te ?
Jupiter
S+ emissions