1.  Twist propagation in Hα surges
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1. Twist propagation in Hα surges Patricia Jibben and Richard C. Canfield 2004, ApJ, 610, 1129 PowerPoint PPT Presentation


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1. Twist propagation in Hα surges Patricia Jibben and Richard C. Canfield 2004, ApJ, 610, 1129 2. Observation of the Molecular Zeeman Effect in the G Band Asensio Ramos et al., 2004, ApJ, 611, L61. 2004 Sep 27 雑誌会速報 J. Kiyohara.

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1. Twist propagation in Hα surges Patricia Jibben and Richard C. Canfield 2004, ApJ, 610, 1129

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1 twist propagation in h surges patricia jibben and richard c canfield 2004 apj 610 1129

  • 1. Twist propagation in Hα surges

  • Patricia Jibben and Richard C. Canfield2004, ApJ, 610, 1129

  • 2. Observation of the Molecular Zeeman Effect in the G Band

  • Asensio Ramos et al., 2004, ApJ, 611, L61

2004 Sep 27 雑誌会速報

J. Kiyohara


Twist propagation in h surges patricia jibben and richard c canfield 2004 apj 610 1129

Twist propagation in Hα surgesPatricia Jibben and Richard C. Canfield2004, ApJ, 610, 1129

- The relationship between surge spin and the stored twist in the

magnetic field was examined.

- Hα spectroheliograms (Mees CCD Imaging Spectrograph)

spectral range : Hα±10Å

2”.3 pixel-1spatial and 0.37Åpixel -1spectral resolution

vector magnetogram (Haleakala Stokes Polarimeter)

Fe I : 6301.5 and 6302.5 magnetogram

- Active region selection criteria

- change of the active region area ⊿a/a>10%

- δor βγδregion - relatively large area ( a > 500μh)

- well sampled with MCCD and HSP

- within ± 45°of central meridian

→396 surges were selected


1 twist propagation in h surges patricia jibben and richard c canfield 2004 apj 610 1129

Hαspectropheliograms and Doppler Shifts

→68% correlation

between surge handedness and

the hemisphere of the Sun

velocity map

white : red shift

black : blue shift

Hαmap

→handedness could be determined in 249


1 twist propagation in h surges patricia jibben and richard c canfield 2004 apj 610 1129

HSP vector magnetograms and αmaps

α>0 : right-handed

left :

vector magnetogram

right :

αmap negative : dashed

positive : solid


1 twist propagation in h surges patricia jibben and richard c canfield 2004 apj 610 1129

Of all the observed surges, only 26 surges could be determined both

the handedness of the surge and the sign of α at its point of origin.

- Most of the surges tend to occur near the edge of a sunspot and

near a boundary separating opposite signs of α.

- A correlation between the stored twist in the magnetic field at the point

of origin and handedness of the surge spin at the 99% confidence level.


Interpretation

Interpretation

Magnetic reconnection of twisted magnetic flux with less

twisted flux explains the correlation.

- energy release will accompany

reconnection, and brightenings are

a common feature of the observed

events.

- if the reconnected field lines do not

have the same twist per unit length,

post-reconnection twist propagation

will take place.

left-handed

right-handed


Observation of the molecular zeeman effect in the g band a asensio ramos et al 2004 apj 611 l61

Observation of the Molecular Zeeman Effect in the G BandA. Asensio Ramos et al., 2004, ApJ, 611, L61

Photospheric bright points observed in G band are seen

with very high contrast.

 →  Theoretical investigation (Uietenbroek et al. 2004)

→ This paper shows

- first observational study ( 4304Å + 4312Å )

NOAA0477 on 2003 Aug. 30

with ZIMPOL (Zurich Imaging Polarimeter)

piezoelastic modulator + linear polarizer

- radiative transfer calculations


1 twist propagation in h surges patricia jibben and richard c canfield 2004 apj 610 1129

Theoretical prediction of the G-band polarization in Sunspot

calculation including both the atomic and CH lines

calculation including only the CH lines

calculation without including any stray-light contamination

In one wavelength location near 4303Å, the overlap of several magnetically

sensitive and nonsensitive CH lines was predicted to produce a single-lobed

Stokes V profile.


1 twist propagation in h surges patricia jibben and richard c canfield 2004 apj 610 1129

calculations

observed V/I

positive polarity

observed V/I

negative polarity


1 twist propagation in h surges patricia jibben and richard c canfield 2004 apj 610 1129

calculations

observed V/I

observed Q/I

in penumbrae

non negligible

linear polarization


1 twist propagation in h surges patricia jibben and richard c canfield 2004 apj 610 1129

conclusion

- The observed polarization profiles confirm the previous theoretical prediction of

the Zeeman effect in the G band.

- Non-negligible Linear polarization was detected in both umbrae and penumbrae.

-preliminary comparison

V/I amplitude is smaller than the theoretical prediction (2000G)

  → an indication of the presence of horizontal inhomogeneities in th

photospheric regions of sunspot umbrae coexisting within the

spatiotemporal resolution element of the observation.

  → these inhomogeneities might be associated with the multitude of

umbral dots.

→linear polarization signal observed in sunspot umbrae could be an

indication that the umbral dot component has inclined magnetic fields.

- The theoretical interpretation of observations of the Zeeman effect in the G band

offers a new diagnostic window for exploring the thermal and magnetic structuring

of the solar photosphere.


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