Search Publications
Spatial Distribution and North-South Asymmetry of Coronal Bright Points from Mid-1998 to Mid-1999
Temmer, M.; Vršnak, B.; Wöhl, H. +5 more
Full-disc full-resolution (FDFR) solar images obtained with the Extreme Ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory (SOHO) were used to analyse the centre-to-limb function and latitudinal distribution of coronal bright points. The results obtained with the interactive and the automatic method, as well as for…
Fractal-Based Fuzzy Technique For Detection Of Active Regions From Solar Images
Revathy, K.; Lekshmi, S.; Nayar, S. R. Prabhakaran
Fractal concepts are used to describe the irregular structures and regions of interest of solar images. The most common and easiest way to extract regions of interest from an image is through segmentation. Segmentation techniques vary from conventional edge-detection mechanism to fuzzy c-means clustering. In this study, the pixelwise local fractal…
Microwave, Optical, EUV, and Hard X-Ray Signature of Possible Coronal Loop Interaction
Ji, Haisheng; Huang, Guangli
In this paper, we present a comprehensive picture for the M2.0 class flare of September 9, 2002 with an extensive multi-wavelength analysis. The flare was observed by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI), the Owens Valley Solar Arrays (OVSA), and Big Bear Solar Observatory (BBSO). At BBSO, the observation was specially made a…
Automated Technique For Comparison Of Magnetic Field Inversion Lines With Filament Skeletons From The Solar Feature Catalogue
Zharkova, V. V.; Aboudarham, J.; Zharkov, S. +3 more
We present an automated technique for comparison of magnetic field inversion-line maps from SOHO/MDI magnetograms with solar filament data from the Solar Feature Catalogue created as part of the European Grid of Solar Observations project. The Euclidean distance transform and connected component labelling are used to identify nearest inversion lin…
Poisson Recoding Of Solar Images For Enhanced Compression
Berghmans, David; Nicula, Bogdan; Hochedez, Jean-François
The amount of useful scientific data that a space-borne telescope produces is often limited by the available telemetry of the platform. General purpose image compression schemes are usually used to compress the image either lossy or losslessly. These schemes do not take into account the fact that pixel values of typical solar images are only known…
Electron Acceleration in the Corona
Simnett, G. M.
The series of nine impulsive, highly collimated beams of near-relativistic electrons seen by ACE/EPAM on 26 and 27 June 2004 occurred at a quiet time with respect to solar flare and CME production. However, they were accompanied by decametric type III radio bursts observed by WIND/WAVES, which had progressively higher starting frequencies, suggest…
Wavelet Spectrum Analysis Of Eit/Soho Images
Delouille, V.; De Patoul, J.; Hochedez, J. F. +2 more
The extreme ultraviolet imaging telescope (EIT) of SOHO offers a unique record of the solar atmosphere for its sampling in temperature, field of view, resolution, duration, and cadence. To investigate globally and locally its topology and evolution during the solar cycle, we consider a multi-scale approach, and more precisely we use the wavelet sp…
Fip Enhancement by Alfvén Ionization
Fletcher, L.; Potts, H. E.; Diver, D. A.
Alfvén ionization is offered as a possible mechanism underlying the enhanced population of low first ionization potential (FIP) species in the solar corona. In this process, the photospheric flow impinging on the magnetic structure of a coronal flux tube collides with, and displaces, ions in the magnetised plasma within the flux tube. This leads t…
The Observational Evidence on the Loop Loop Interaction in a Flare CME Event on April 15, 1998
Huang, G. L.; Tang, Y. H.; Wu, G. P. +1 more
The evolution of the soft X-ray and EUV coronal loops related to the April 15, 1998 solar flare-CME event is studied with multiwavelength observations including hard X-rays (BATSE), microwaves (NoRP, CNAO) and magnetograms (SOHO/MDI), as well as images from Yohkoh/SXT and SOHO/EIT at 195 Å. It is shown that: (1) two soft X-ray and EUV loops rose, …
Energetic Electrons in Loop Top and Footpoint Microwave Sources
Zhou, A. H.; Su, Y. N.; Huang, G. L.
We have studied two microwave events with one-loop top (LT) and two-footpoint (FP) sources observed at 17 and 34 GHz by the Nobeyama Radioheliograph (NoRH). The microwave brightness peak is located near the FPs of the flare loop for one event, but near the LT for the other event. The microwave spectra of the FP sources are considerably softer (by …