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The radio signature of twisted magnetic ropes and reconnection site in the low corona
Grechnev, V. V.; Huang, G. L.; Altyntsev, A. T. +2 more
A solar radio burst on 25 August 1999 with fine structures (FS) at 4.5-7.5 GHz is studied in this paper. The FS started about one minute prior to the main burst. The maximum emission took place at 4-5 GHz for the FS, and at 10-11 GHz for the main burst, respectively. The time profiles at 4.5-7.5 GHz coincide very well with those of hard X-rays (fr…
Carbon and Oxygen Coronal Line Intensities for the Electron κ-DistributionI
Dzifčáková, Elena; Kulinová, Alena
The ionization and excitation equilibrium of C and O for the electron κ-distribution in the solar corona is studied. The change of the distribution shape changes the ionization, recombination and excitation rates. These changes influence the relative ion abundance and the level populations. The ionization peaks are wider and the level populations …
The analogy between sunquakes and water waves
Podesta, J. J.
To investigate the seismic waves generated at the surface of the convection zone by a sunquake, the solar convection zone is modeled as an incompressible fluid layer of finite depth which is excited by a pressure pulse just above the solar surface. Solutions for the surface displacement ζ as a function of time are obtained by solving the linearize…
High-Energy 3He-Rich Solar Particle Events
Kocharov, Leon; Torsti, Jarmo; Thompson, Barbara J. +2 more
Energetic particle observations of the ERNE instrument on board SOHO enable measurements of 3He and 4He fluxes beyond 15 MeV nucleon−1 with good statistical resolution. We report results of a survey of the ERNE observations covering the period from 8 February 1999 to 6 December 2000. We find 10 and 5 days during wh…
Repeated Flaring from Loop-Loop Interaction
Pohjolainen, S.
A series of solar flares was observed near the same location in NOAA active region 8996 on 18-20 May 2000. A detailed analysis of one of these flares is presented where the emitting structures in soft and hard X-rays, EUV, Hα, and radio at centimeter wavelengths are compared. Hard X-rays and radio emission were observed at two separate loop footpo…
The Energy Equation in the Lower Solar Convection Zone
Durney, Bernard R.
As a consequence of the Taylor-Proudman balance, a balance between the pressure, Coriolis and buoyancy forces in the radial and latitudinal momentum equations (that is expected to be amply satisfied in the lower solar convection zone), the superadiabatic gradient is determined by the rotation law and by an unspecified function of r, say, S'Ω<…
Flares From the Giant ar 9433 on 24 April 2001
Uddin, Wahab; Chandra, Ramesh; Joshi, Anita
We present Hα CCD observations of three small-to-medium-size two-ribbon flares observed in the giant AR 9433 on 24 April 2001. Flare observations at other associated wavelengths (e.g., soft X-rays (SXR), hard X-rays (HXR), microwaves (MW)) obtained from archives are also presented and compared. We have tested the Neupert effect for the most energe…
Periodicities Near 160 Minutes in Flare Occurrence
Bai, Taeil
The 160.01-min periodicity was originally found from line-of-sight velocities of the photosphere, and Kotov and Tsap reported a detection of the same periodicity in flare occurrence times. Intrigued by this, I analyze occurrence times of flares of cycles 19-23 to investigate periodicities in the neighborhood of 160 min, cycle by cycle. The 160.01-…
Acceleration Effects in MDI Magnetogram Data
Norton, A.; Settele, A.
Acceleration effects are found in the Michelson Doppler Imager (MDI) magnetogram data because changes in the line profiles during the 30-s measurement are introduced by underlying p-mode velocity variations. This imparts an oscillatory component to the magnetic flux signal. Simulated profiles using Maltby M and Harvard Smithsonian Reference Atmosp…
The Magnetic Helicity Budget of a cme-Prolific Active Region
Mandrini, C. H.; Culhane, J. L.; Démoulin, P. +3 more
Coronal mass ejections (CMEs) are thought to be the way by which the solar corona expels accumulated magnetic helicity which is injected into the corona via several methods. DeVore (2000) suggests that a significant quantity is injected by the action of differential rotation, however Démoulin et al. (2002b), based on the study of a simple bipolar …