Transcript THEMIS and the Amazing Flux Rope

THEMIS
and
the Amazing Magnetic Flux Rope
D. G. Sibeck
Project Scientist
NASA/Goddard Space Flight Center
Where does the energy come
from that drives the polar aurora?
Sun
and Magnetosphere
We want to testing advanced
numerical simulations
Looped Simulation from Nick
Omidi:
Shows generation of FTE
bulges/blobs moving antisunward
from points of origin near the
subsolar point.
Are they real?
Flux Ropes or Boundary Waves?
Let THEMISthe blindfolded
Greek goddess
of impartial
justice decide!
AEDCB
Flux ropes
bulge outward
in both directions
AEDCB
Boundary waves
bulge one way
or the other
Observation and Interpretation
10.0
B (nT)
THEMIS May 20, 2007
40
Magnetosphere
30 nT
THEMIS-A
10.5
Sphere
B (nT)
0
40
THEMIS-E
11.0
Y (RE)
B (nT)
Bx (nT)
400
THEMIS-D
THEMIS-D
B (nT)
D
11.5
E
 Bxy
A
-,+
12.0
0
12.5
-40
40
THEMIS-C
Sheath
10 nT
Magnetosheat h
0
B (nT)
B
C
0
40
20 nT
40
13.0
8.0
THEMIS-B
7.5
7.0
6.5
0
22:01
22:02
UT
22:03
22:04
5.5
5.0
We used the 5 THEMIS spacecraft
X (R )
to construct cross-sections indicating
a flux rope detached from the
Dusk MP
magnetosphere
E
22:00
6.0
Flux Ropes Power the
Magnetosphere!
30 kiloVolt battery in space
+
Flux rope
1,500,000
pumps
Amps
650,000
Amp current
into +the arctic!
-
-
1 Earth Radius
Summary
• 1. We used the 5 THEMIS spacecraft to identify a giant
magnetic flux rope at the outer boundary of the Earth’s
magnetic field.
• 2. We showed that the flux rope was detached from the
magnetopause.
• 3. Flux ropes like this one apply 30 kiloVolts to the Earth
and drives 650,000 amp currents into the polar cap.