Search Publications
Giant Meterwave Radio Telescope observations of an M2.8 flare: Insights into the initiation of a flare-coronal mass ejection event
Janardhan, P.; Kundu, M. R.; White, S. M. +3 more
We present the first observations of a solar flare with the GMRT. An M2.8 flare observed at 1060 MHz with the GMRT on 17 November 2001 was associated with a prominence eruption observed at 17 GHz by the Nobeyama radioheliograph and the initiation of a fast partial halo CME observed with the LASCO C2 coronagraph. Towards the start of the eruption, …
Photospheric and chromospheric oscillations in the base of coronal holes
Kobanov, N. I.; Makarchik, D. V.; Sklyar, A. A.
In this paper we carry out an analysis of the spatial-temporal line-of-sight velocity variations measured in the chromospheric (Hα, Hβ) and photospheric (Fei 6569 Å, Fei 4864 Å, Nii 4857 Å) lines at the base of 17 coronal holes. Time series of a duration from 43 to 120 min were recorded with the CCD line-array and the CCD matrix. Rather frequently…
Detection of the Long-Term Microwave `Darkening' Before the 14 July 2000 Flare
Tokhchukova, Susanna; Bogod, Vladimir
A gradual microwave darkening during several days of the preflare phase in the active region (AR) NOAA 9077, before the powerful proton event on 14 July 2000 was detected. The associated change of the circular polarization structure in the form of narrow-band double inversion of the sign was marked. The effects were revealed in a wide range of rad…
Structure and Evolution of the Transition Region Network Observed in he ii λ304
Venkatakrishnan, P.; Ravindra, B.
The length scale and life time of the transition region network cells were studied using He ii λ304 filtergrams. The temporal structure function was calculated from spatially aligned He ii λ304 images. The estimated life time of the network cell was about 27 hr. We compared this life time with the life time of photospheric magnetic network and of …
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<…