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Scientific Collaboration of NAOC Facilities

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Scientific Collaboration of. NAOC ... Vector magnetograph at Fe5324 & line-of-sight magnetograph at H ... Full-disk vector magnetograph (under calibration) ... – PowerPoint PPT presentation

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Title: Scientific Collaboration of NAOC Facilities


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

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

4
HSOS vector magnetograms showing Flux evolution
and Shear development
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), 251-382

6
  • 3D null points in AR 10720

Linear force-free field lines, reconstructed from
the BBSOs vector magnetogram of 2005 Jan 15,
2140 UT. The background is H-a image of the same
time.. We even find a loop-like fan in the green
one
7
Resolve the 180ambiguity 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

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

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?

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
11
We do need both very high resolution very high
sensitivity
Roughly the same size of FOV, 31?X31?
Very high resolution
High sensitivity
Bergers et al. 2004 AA 428, 613
Wang et al. 1995 Solar Phys. 160, 227
Lites, 2002, ApJ 573,431
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