Small Scale Magnetic Reconnection in the Solar Wind. A.C. Foster 1 , C.J. Owen 1 , A.N. Fazakerley 1 , I. J. Rae 1 , C. Forsyth 1 , E. Lucek 2 , H. Rème 3 1. UCL, Mullard Space Science Laboratory, Surrey, UK 2. Imperial College, London, UK 3. CNRS, IRAP, Toulouse, France 4. Cluster Active Archive UCL DEPARTMENT OF SPACE & CLIMATE PHYSICS MULLARD SPACE SCIENCE LABORATORY
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Small Scale Magnetic Reconnection in the Solar Wind.
UCL DEPARTMENT OF SPACE & CLIMATE PHYSICS MULLARD SPACE SCIENCE LABORATORY. Small Scale Magnetic Reconnection in the Solar Wind. A.C. Foster 1 , C.J. Owen 1 , A.N. Fazakerley 1 , I. J. Rae 1 , C. Forsyth 1 , E. Lucek 2 , H. Rème 3 UCL, Mullard Space Science Laboratory, Surrey, UK - PowerPoint PPT Presentation
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Small Scale Magnetic Reconnection in the Solar Wind.
A.C. Foster1, C.J. Owen1, A.N. Fazakerley1, I. J. Rae1, C. Forsyth1, E. Lucek2, H. Rème3
1. UCL, Mullard Space Science Laboratory, Surrey, UK
2. Imperial College, London, UK
3. CNRS, IRAP, Toulouse, France
4. Cluster Active Archive
UCL DEPARTMENT OF SPACE & CLIMATE PHYSICSMULLARD SPACE SCIENCE LABORATORY
Magnetic Reconnection Observables
• First published study of solar wind reconnection made by Gosling, 2005.
• Bifurcated current sheet
• Magnetic field rotations over current sheets
• Enhanced plasma jet / reconnection exhaust
Reconnection Exhaust
Reconnection Exhaust Adapted from
Gosling, J.T. (2005)
Inflow
Inflow
Inflow
Inflow
Magnetic Field LinesCurrent Sheet
A1 A2
B
B
Phan, T.D (2006)
• Unconstrained boundary conditions
• Multiple spacecraft observations
• Time scales ≤ few hours
• Length scales ~100s RE
• Different plasma conditions than frequently studied (e.g. Magnetopause / magnetotail)
Advantages in studying Reconnection in the Solar Wind
Earth
ACE
Cluster
Wind
Exhaust
To Sun
Jet
Jet
BM
Solar Wind
Direction
Phan, T.D (2006)
Previous study of reconnection event 02/02/2002
• Previous results have suggested that reconnection in the solar wind is fundamentally extended and non patchy.
• Is this always the case?
• Study magnetic reconnection structures
–Test the consistency of the temporal and spatial structure of magnetic reconnection from large scales to small scales
–using the 4 Cluster spacecraft; multi-scale capacity
Aim of Project
Case Study: Event 2/3/2006|B
| (nT
)|V
| (km
/s)
Vy
(nT
)
Total -- X -- Y -- Z --
400
380390
370
10
-100
-20
0
4
8
2
6
0
4
-2
2
-370
-390-380
-40040
2030
10
B (
nT)
Vx
(km
/s)
Vz
(nT
)
37m00s 37m30s 38m00s 38m30s 39m00s 39m30s 40m00s
Universal Time
Cluster 3 magnetic field and ion velocity data in GSE
Event 2/3/2006: Characteristics
• Magnetic rotation over the event: 71°
Total -- X -- Y -- Z --
37m00s 37m30s 38m00s 38m30s 39m00s 39m30s 40m00s
Universal Time
Event 2/3/2006: Characteristics
• Magnetic rotation over the event: 71°
• Angle between two main current sheets: 33°
Adapted from Gosling, J.T. (2005)
InflowInflow
Inflow
Magnetic Field LinesB
B
Reconnection Exhaust
InflowInflow
Current Sheet
A1
A2
33°
Event 2/3/2006: Characteristics
• Magnetic rotation over the event: 71°
• Angle between two main current sheets: 33°
• Low plasma β either side of the event
0
1
2
3
Pla
sma
β
Cluster 3 plasma β
37m30s 38m30s 39m30s37m00s 38m00s
Universal Time
• Magnetic rotation over the event: 71°
• Angle between two main current sheets: 33°
• Low plasma β either side of the event
• Alfvèn speed approximately 43km/s
Cluster 3 Alfvèn Velocity
Alfv
èn V
eloc
ity k
m/s
37m30s 38m30s 39m30s37m00s 38m00s
Universal Time
Event 2/3/2006: Characteristics
40
50
42
4446
48
Event 2/3/2006: Consistency
• Consistent with previous results
•Double magnetic field rotation that bounds an ion velocity increase.
1
B (
nT)
|V|
km/s
Cluster 3 magnetic field in GSE co-ordinates and ion Velocity
Event 2/3/2006: Consistency
• Consistent with previous results
•The changes in V and B are correlated on one edge of the exhaust and anti-correlated on the other.
1
B (
nT)
|V|
km/s
Cluster 3 magnetic field in GSE co-ordinates and ion Velocity
Event 2/3/2006: Consistency
• Consistent with previous results
•The Walen test is satisfied for the two rotations seen at Cluster 3.
C1
C2
C3
C4
∆C1 = 0.00
∆C2 = 35.50
∆C3 = -0.09
∆C4 = 16.6
Magnetic field in GSE co-ordinates for the 4 Cluster spacecraft
Also seen at ACE and Wind
B (
nT)
B (
nT)
B (
nT)
|V| (
kms-1
|V| (
kms-1
|V| (
kms-1
6420
-2-4
6420
-2-4
6420
-2-4
440420
400380
420400
380360
420400
380360
15m00s 15m30s 16m00s 16m30s 17m00s
Universal Time
Conclusion and Discussion
• In the solar wind the current picture is of large-scale non-patchy events
•This study looks at the small scale structure
•Reconnection seen at Cluster. Similar current sheets at ACE and Wind but no evidence for ion velocity enhancements.
• Large overall structure current sheet structure (100s RE) but there are small scale differences on the 10,000km scale.
● Baumjohann, W. (1997): Wolfgang Baumjohann and Rudolf A. Treumann. Basics of Space Plasma Physics. Imperial College Press, 1997.
● Priest, E. R. (1984): Priest, E. R. (1984), Solar Magneto-Hydrodynamics, Geophys. Astrophys.Monogr. Ser., Springer, New York.
● Phan, T. D. (2006): T. D. Phan, J. T. Gosling, M. S. Davis, R. M. Skoug, M. Øieroset, R. P. Lin, R. P. Lepping, D. J.McComas, C. W. Smith, H. Reme, and A. Balogh. A magnetic reconnection X-line extending more than 390 Earth radii in the solar wind. Nature, 439:175–178, January 2006.
● Gosling (2007): J. T. Gosling, S. Eriksson,L. M. Blush,T. D. Phan,J. G. Luhmann,D. J. McComas,R. M. Skoug,M. H. Acuna,C. T. Russell, and K. D. Simunac. Five spacecraft observations of oppositely directed exhaust jets from a magnetic reconnection X-line extending > 4.26 106km in the solar wind at 1 AU
References
UCL DEPARTMENT OF SPACE & CLIMATE PHYSICSMULLARD SPACE SCIENCE LABORATORY
UCL DEPARTMENT OF SPACE & CLIMATE PHYSICSMULLARD SPACE SCIENCE LABORATORY
Event 2/3/2006: VisualisationM
inim
um V
aria
nce
Dire
ctio
n
Min
imum
Var
ianc
e D
irect
ion
500
0-5
000
400
0-4
000
-10000 0 10000 -10000 0 10000Maximum Variance Direction Maximum Variance Direction