3,444 research outputs found
Two Solar Tornadoes Observed with the Interface Region Imaging Spectrograph
The barbs or legs of some prominences show an apparent motion of rotation,
which are often termed solar tornadoes. It is under debate whether the apparent
motion is a real rotating motion, or caused by oscillations or
counter-streaming flows. We present analysis results from spectroscopic
observations of two tornadoes by the Interface Region Imaging Spectrograph.
Each tornado was observed for more than 2.5 hours. Doppler velocities are
derived through a single Gaussian fit to the Mg~{\sc{ii}}~k~2796\AA{}~and
Si~{\sc{iv}}~1393\AA{}~line profiles. We find coherent and stable red and blue
shifts adjacent to each other across the tornado axes, which appears to favor
the interpretation of these tornadoes as rotating cool plasmas with
temperatures of K- K. This interpretation is further supported by
simultaneous observations of the Atmospheric Imaging Assembly on board the
Solar Dynamics Observatory, which reveal periodic motions of dark structures in
the tornadoes. Our results demonstrate that spectroscopic observations can
provide key information to disentangle different physical processes in solar
prominences.Comment: 14 figures, accepted by Ap
KN and KbarN Elastic Scattering in the Quark Potential Model
The KN and KbarN low-energy elastic scattering is consistently studied in the
framework of the QCD-inspired quark potential model. The model is composed of
the t-channel one-gluon exchange potential, the s-channel one-gluon exchange
potential and the harmonic oscillator confinement potential. By means of the
resonating group method, nonlocal effective interaction potentials for the KN
and KbarN systems are derived and used to calculate the KN and KbarN elastic
scattering phase shifts. By considering the effect of QCD renormalization, the
contribution of the color octet of the clusters (qqbar) and (qqq) and the
suppression of the spin-orbital coupling, the numerical results are in fairly
good agreement with the experimental data.Comment: 20 pages, 8 figure
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