Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu...
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![Page 1: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/1.jpg)
Observations on Current Sheet and Magnetic
Reconnection in Solar Flares
Haimin Wang and
Jiong QiuBBSO/NJIT
![Page 2: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/2.jpg)
Background
Magnetic reconnection at low corona is the drive of flares. Recent observations have provided indirect evidence of magnetic reconnection as depicted by the standard (eruptive) flare model.
The rate of magnetic reconnection may be derived from flare observations using sound assumptions and approximations.
Current sheet is the most important structure in the magnetic reconnection process.
![Page 3: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/3.jpg)
How do scientists “observe” magnetic Reconnection and Current Sheet, the driver of solar flares?
![Page 4: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/4.jpg)
“observe” magnetic reconnection in a standard flare configuration
(Courtesy of Terry Forbes )
![Page 5: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/5.jpg)
flare loop arcade and two ribbons in EUV
TRACE Fe 19.5nm
![Page 6: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/6.jpg)
two-ribbon flare observed in different wavelengths
![Page 7: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/7.jpg)
Yohkoh SoHO RHESSILoop-top hard X-ray source (Masuda et al. 1994) and super-hot source (Tsuneta 1997)
High-temperature structure indicative of current sheet (Ko et al. 2003)
Hard X-ray sources at two ends of RCS (Sui et al. 2003).
High temperature ridges along outer loops (Tsuneta 1996)
Evidence of chromospheric evaporation (Czaykowska et al. 1999)
Soft X-ray jets (Shimizu 1994, 1995)
Signatures of magnetic reconnection and Current sheet in the corona: satellite observations
![Page 8: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/8.jpg)
Here put a couple of figures from satelliteObservations.
Masuda flare: hard X-ray source above the loop top(Masuda et al. 1994)
YOHKOH
![Page 9: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/9.jpg)
soft X-ray jet as indication ofreconnection outflow
(Shimizu 1994)
soft X-ray high temperature ridges along outer or newly formed loops
(Tsuneta 1996)
YOHKOH
![Page 10: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/10.jpg)
high temperature structure indicative of current sheet (Ko et al. 2003)
X-ray sources at two ends of current sheet (Sui et al. 2003)
SOHO
RHESSI
![Page 11: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/11.jpg)
The rate of magnetic reconnection
can be inferred from some sorts of
observations using sound
assumptions and approximations.
![Page 12: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/12.jpg)
Magnetic reconnection
is the driver of
solar flares.
Magnetic reconnection rate
is deduced by measuring
expansion of flare ribbons
across magnetic fields.
E field
corona
surface
![Page 13: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/13.jpg)
Physical approach : Forbes & Lin (2000)
Ec: electric field along the reconnecting current sheet (RCS) at the corona
V11
l
![Page 14: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/14.jpg)
M1.0 flare on 2000 September 12
![Page 15: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/15.jpg)
Ribbon 1
Ribbon 2
electric field(V/cm)
voltage drop (Mx/s)
![Page 16: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/16.jpg)
magnetic reconnection rate and flare emission
11 12 13 14 hr
.8
.6
.4
.2
.0
4
3
2
1
0
flare soft X-ray emission rate
E field (V/cm)
flux rate(1e+18 Mx/s)
![Page 17: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/17.jpg)
X1.6 flare on 2001 October 19
![Page 18: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/18.jpg)
Electric field(v/cm) Voltage drop
(Mx/s)
Ribbon 1
Ribbon 2
![Page 19: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/19.jpg)
flux rate (1e+18 Mx/s)
16:20 16:30 16:40 16:50 17:00
E field (V/cm)
flare microwave emission at 10 GHz
6
4
2
0
7.5
5.0
2.5
0.0
Magnetic reconnection rate and flare non-thermal emission
![Page 20: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/20.jpg)
rate of total magnetic
flux reconnected
rate of total magnetic
flux reconnected
E field
E field
flare
flare
flux rate
flux rate E field
E field
flare
flareEither way, it
evolves along with
flare high-energy
emission.
two ways to measure
the magnetic
reconnection rate 11 12 13
14
16:10 16:20 16:30 16:40 16:50 17:00
event 1
event 27.5
5.0
2.5
0.0
0.8
0.4
0.0
![Page 21: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/21.jpg)
They are all driven
magnetically.
Coronal mass ejections
are often accompanied by
filament eruptions and flares.
![Page 22: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/22.jpg)
correlation
between
mass flight
and
flare emission
(Zhang et al. 2001)
CME
flare
In some flare-CME events, acceleration of CMEs and magnetic reconnection that drives flares are closely related.
![Page 23: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/23.jpg)
(Lin et al. 2004)
CME
filament
two-ribbon flare
A schematic flux rope model for CME and flare
![Page 24: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/24.jpg)
mass acceleratio
n
magnetic reconnection
flare emission
![Page 25: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/25.jpg)
Strong Correlation Between Magnetic Reconnection Rate and Filament Acceleration
(Jing et al., 2004, Ap.J. to be submitted)
![Page 26: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/26.jpg)
Weaker Correlation Between Magnetic Reconnection Rate and CME Acceleration (Jing et al., 2004, Ap.J. to be submitted)
![Page 27: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/27.jpg)
The derived magnetic reconnection rate is temporally correlated with flare non-thermal emission and mass acceleration of core flux rope ejection.
![Page 28: Observations on Current Sheet and Magnetic Reconnection in Solar Flares Haimin Wang and Jiong Qiu BBSO/NJIT.](https://reader030.fdocuments.us/reader030/viewer/2022032702/56649cb15503460f94976358/html5/thumbnails/28.jpg)
SUMMARY
Indirect Evidence of Current Sheets and Magnetic Reconnection
• High temperature region in Helmet Structure
• Plasma outflow above flare loop• Loop top HXR source • Organized separation of flare ribbons