studying solar wind magnetic reconnection events using cluster. a.c. foster 1, c.j. owen 1, a.n....
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Studying Solar Wind Magnetic Reconnection Events using Cluster.
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
UCL DEPARTMENT OF SPACE & CLIMATE PHYSICSMULLARD SPACE SCIENCE LABORATORY
Magnetic Reconnection Observables
• First 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)
Magnetic rotation at current sheets
Previous study of reconnection event 02/02/2002
Data from Cluster 3 in GSE Total -- X --
Y -- Z --
|B| (
nT)
B (
nT)
|vel
ocity
| (km
/s)
|vel
ocity
| (km
/s)
velo
city
(km
/s)
Universal Time
• 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)
B (
nT)
|Vel
ocity
| (km
/s)
Vel
ocity
_x (
km/s
)
Vel
ocity
_z (
nT)
Vel
ocity
_y (
km/s
)
Den
sity
Total -- X -- Y -- Z --
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.
•The Walen test has been satisfied.
Event 2/3/2006: Characteristics
• Magnetic rotation over the event: 550
• Angle between two main current sheets: 330
• Low plasma β either side of the event, increase of plasma β during the event
•Alfven speed approximately 43km/s
Event 2/3/2006: Visualisation
Maximum Variance DirectionMaximum Variance Direction
Min
imum
Var
ianc
e D
irect
ion
Min
imum
Var
ianc
e D
irect
ion
10000-10000 0
100
00-1
0000
0
-10000 100000
-100
000
100
00
Courtesy of C. Forsyth, C.Owen, I.J. Rae
CS1 -- CS2 – residual velocity B Field
CS1 -- CS2 – residual velocity B Field
Initial configuration
Configuration with 2% alteration in background
solar wind speed
Event 2/3/2006
|B| (
nT)
8
0
8
0
|B| (
nT)
|B| (
nT)
8
0 0
8
|B| (
nT)
37m30s 40m00s 37m30s 40m00s
37m30s 37m30s40m00s 40m00s
C4C3
C2C1
4
-2
4
44
-2 -2
-2
B (
nT)
B (
nT)
B (
nT)
B (
nT)
Universal Time Universal Time
Universal TimeUniversal Time
Total -- X -- Y -- Z --
Also seen at ACE
• Similar current sheets seen at ACE. Situated approximately 200RE away from the Cluster spacecraft
• Large overall structure (100s RE) but there are small scale differences on the 10,000km scale.
Discussion
Conclusions
• Small scale differences. In the solar wind the picture is of large scale, non patchy events
• Not all of the reconnection events fit the simple gosling bifurcated current sheet with the reconnection outflow between the two.
● 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.
● Gosling, J.T (2005): J.T. Gosling, R.M. Skoug, D.J. McComas, C.W. Smith, J. Geophys. Res. 110, A01107, 2005
● 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
Cluster Configuration
2/3/2006
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