1. Scientific Collaboration of NAOC Facilities & Solar-B
Jingxiu Wang
National Astronomical Observatories, CAS

2. Facilities at National Astronomical Observatories of Chinese Academy
Vector magnetograph at Fe5324 Å & line-of-sight magnetograph at H
Full disk Ha filtergraphs with 2kx2k CCDs at Huairou & Yunnan
High resolution Ha telescope of Purple Mount.
Broad-band radio dynamic spectrometers (NAOC including Yunnan Obs., Purple Mountain Obs.)
Multiple-wavelength imaging spectragraph (Purple Mount….), including He10830 Å
Full-disk vector magnetograph (under calibration)
Near-infrared (to1.56 ) 1 meter solar tower with Stokes-polarimetry
Radioheliograph at decimeter-meter wavebands
2019/1/1
The 17th SOT meeting

3. Possible Collaborations
Coordinated software development
Jointed data analysis and interpretation for more effective usage of the ground data with combination of Solar-B observations and better exploration of theoretical knowledge
Exchange of scientists with the emphasis on a better and deeper education of young scientists and Ph.D. students
2019/1/1
The 17th SOT meeting

4. HSOS vector magnetograms showing Flux evolution and Shear development
2019/1/1
The 17th SOT meeting

5. Studies based on the measurements of solar vector magnetic fields¤
Magnetic connectivity (-loop, U-loop, O-loop …?)
3D structures in solar atmosphere (non-linear force-free field extrapolation)* (Yan & Sakurai)
Magnetic complexity
- topology skeleton (3D null*, spine, fan, separatrix)
- twist & writhe (magnetic helicity, current helicity*)
Magnetic non-potentiality (currents*, magnetic shear*, vector shear angle*, free energy*)
* Software basically available
¤ Reviewed by Wang, in Fund. Cosmic Phys. 20(1999),
2019/1/1
The 17th SOT meeting

6. 3D null points in AR 10720
Linear force-free field lines, reconstructed from the BBSO’s vector magnetogram of 2005 Jan 15, 21:40 UT. The background is H-a image of the same time.. We even find a loop-like fan in the green one
2019/1/1
The 17th SOT meeting

7. Resolve the 180°ambiguity in field azimuth
The ambiguity is an intrinsic defect of Zeeman
Measurements. An additional constraint from non- Zeeman effect is required to solve the problem
Objective ways
Potential assumption*
Force-free assumption*
Divergence free theorem
Continuity assumption
Empirical judgement+
Flux emergence history
H fibril alignment
Helicity law
+ interactive software developed
2019/1/1
The 17th SOT meeting

8. A few remarks
Fourier Solutions are often convenient (some type of smoothing automatically taken)
Potential & linear force-free extrapolation* &
Vertical current calculation* (Wang et al. 1996)
- Vector potential and relative magnetic helicity (Chae 2001)
Interactive procedures sometimes are necessary
Say, if we like to get evolution along magnetic neutral line* (or zone), we may use `channel.pro’
Long time-sequence is important in studying vector field evolution
Removing projection effect is required*
2019/1/1
The 17th SOT meeting

9. Moving magnetic features – a mystery in solar physics
Current carrying?
Geometry?
Classification (Shine & Title 2000)
-- bipolar
-- uni-polar (polarity referring to parent sunspot)
Why they are different?
Physical nature
-- propagating kink?
-- peeled off flux from sunspot?
-- new flux emergence at small scale?
Relation to parent sunspot?
Relation to flare/CME activity?
2019/1/1
The 17th SOT meeting

10. Quiet Sun Magnetic Field Studies
Is there a magnetic dichotomy, or a quantization, or a spectrum distribution?
Intrisic field strength
Flux distribution function (interactive flux measurements*)
Correlation with plasma flow patterns
Correlation with heating of solar atmosphere
Influence on opening coronal structure
We know too little about coronal hole & polar fields
2019/1/1
The 17th SOT meeting

11. We do need both very high resolution & very high sensitivity
Roughly the same size of FOV, 31X31
Very high resolution
High sensitivity
Wang et al Solar Phys.
160, 227
Lites, 2002, ApJ 573,431
Bergers et al A&A 428, 613
2019/1/1
The 17th SOT meeting