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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2004 Sep 27 雑誌会速報
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
Hαspectropheliograms and Doppler Shifts
between surge handedness and
the hemisphere of the Sun
white : red shift
black : blue shift
→handedness could be determined in 249
HSP vector magnetograms and αmaps
α＞0 : right-handed
αmap negative : dashed
positive : solid
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.
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
－ if the reconnected field lines do not
have the same twist per unit length,
post-reconnection twist propagation
will take place.
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
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.
－ 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.
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
→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.