Lecture Note
Global Magnetospheric Dynamics of Jupiter and Saturn Revealed by ENA Imaging Pt 1
-
University:
Boston University -
Course:
CAS AS 701 | Introduction to Astrophysics Academic year:
2019
-
Views:
315
Pages:
20
Author:
CometConductor
Global Magnetospheric Dynamics of Jupiter and Saturn Revealed by ENA
Imaging
Saturn
Jupiter POSTER: In Search for a Self-Consistent Hypothesis for Magnetospheric
Periodicities: Effects of the Shielding E-field Produced by the Partial Ring Current
Shielding effects on the
terrestrial plasmasphere Saturn
ENA imaging
Jupiter Saturn
Jupiter
Energization
Jia et al., MAPS, [2011]
Keika et al. [2010]
Large-scale injections appear in the
night side magnetosphere
Energization most likely caused by
the “dipolarizations” following
plasmoid releases
Heavy ions are more effectively
energized than lighter Saturn
Jupiter
Energization: Earth comparison
Ions are efficiently energized during rapid magnetic field reconfigurations.
Shown are model results of O+ for terrestrial substorms. Similar
mechanisms are probably at work also at Mercury and Saturn. Saturn
Jupiter
Transport
Brandt et al. [2008] Saturn
Jupiter
Transport
10 keV
100 keV
Typical in-situ dispersion signatures indicating
injections of different ages and sizes.
Simulation showing one
possible global distribution
that
reproduces
the
dispersion observed in-situ. Saturn
Jupiter
Force Balance: 3D Current System
force balance
current continuity
J
B || J
s B
JB P
J 0
particle motion [Parker, 1957]
The main phase ring current system (“Region-2”) is highly asymmetric
and is driven by the pressure of the inner magnetosphere. Saturn
Jupiter
Periodicity: ENA and SKR
“ENA injections “ simultaneous with
SKR [Mitchell et al., 2009]
ENA injections simultaneous with
in-situ observation of a plasmoid
release [Hill et al., 2008]
SKR most likely driven by (1)
pressure-driven currents from
energetic particles and/or (2) flowshear in the fast-flow region
Lifting the veil:
Periodic plasmoid release the most likely driver of the
magnetospheric periodicities
Dual periodicities in ENA data?
Not clear yet…see Carbary’s talk! Saturn
Periodicity: Magnetic field
Preliminary estimations
demonstrate that the injected
plasma pressure and subsequent
drift can account for the field
perturbations, at least around the
equator [Brandt et al., 2010]
More rigorous effort under way,
where the field perturbations
from a rotating PRC is added to a
bkgrd field model
The background field model is an
updated version and faster version
of KMAG06 including all data
[Tsyganenko, Khurana and
Brandt]
Jupiter Saturn
Jupiter
Periodicity: Magnetic field
Preliminary estimations
demonstrate that the injected
plasma pressure and subsequent
drift can account for the field
perturbations, at least around the
equator [Brandt et al., 2010]
More rigorous effort under way,
where the field perturbations
from a rotating PRC is added to a
bkgrd field model
The background field model is an
updated version and faster version
of KMAG06 including all data
[Tsyganenko, Khurana and
Brandt]
Brandt et al., Geophys. Res. Letters, 2010 Saturn
Jupiter
Neutral gas
Dialynas et al., in preparation, 2011.
Brandt et al., PSS, 2011. Saturn
Solar wind control
Brandt et al., AGU, 2006.
Jupiter
INCA at Saturn: clear solar wind
response
INCA at Jupiter: 2x variations.
Solar wind response TBD. Saturn
Jupiter
ENA imaging
INCA image from 150 RJ taken in 50-80 keV
H [Mitchell et al., 2004]
Mitchell et al., 2004
Europa
torus
Cassini/UVIS (S-band emissions) Saturn
Jupiter
ENA imaging: Simulations
Neutral gas [Smyth et al., 2005]
Energetic ions [Mauk et al., 2004] Saturn
ENA imaging: Simulations
Jupiter Saturn
Jupiter
Energization
transient injection
transient injection
adiabatic increase
current sheet
modulation
Transient, quasi-periodic injections are seen in in-situ data, but it is nearly impossible
to discern their global spatial and temporal distribution and evolution. Data taken
from Selesnick et al. [2001]. Saturn
Jupiter
Energization
Intensities
Spectral slope
Intensities and spectral slopes of heavies increase more than for lighter
ions every ~3 days. Is this the same non-adiabatic mechanism that is at
work at Earth? Saturn
Jupiter
Solar wind control?
“quiet”
“active”
Galileo measurements strongly indicate that “ storms ” occur in Jupiter ’ s
magnetosphere. Particle signatures similar to response of solar wind pressure
increase [Mauk et al., 1999]. Summary
Saturn
Evidence for efficient energization of heavy ions….just like at Earth and Jupiter
ENA and SKR intimately related. Link is probably (1) pressure-driven currents, and/or
(2) flow-shear driven currents in the fast flow in the post midnight sector seen in Jia
et al. model.
Field periodicities caused by rotating partial ring current (hot and/or cold)
Solar wind control apparent (Pressure or speed)
Jupiter
Strongest ENA intensities from Torus region
ENA imaging potentially resolve large-scale injections. Are they quasi-periodic? How
do they relate to radio emissions?
Evidence for efficient energization of heavy ions….just like at Earth and Saturn
Solar wind control not known, but could be addressed by ENA imaging
Global Magnetospheric Dynamics of Jupiter and Saturn Revealed by ENA Imaging Pt 1
of 20
Report
Tell us what’s wrong with it:
Thanks, got it!
We will moderate it soon!
Free up your schedule!
Our EduBirdie Experts Are Here for You 24/7! Just fill out a form and let us know how we can assist you.
Take 5 seconds to unlock
Enter your email below and get instant access to your document