Community of European Solar Radio Astronomers – Page 27

Synchrotron Radio Emission from a Fast Halo Coronal Mass Ejection
by Tim Bastian

2007-12-27

Coronal and interplanetary (IP) type II radio emissions are widely believed to result from the interaction of a super-Alfvenic shock with the coronal and/or the interplanetary medium, producing plasma radiation at the fundamental and/or harmonic of the electron plasma frequency. In the case of coronal type II radio bursts, the nature of the shock driver remains controversial: flare blast waves, flare ejecta, and coronal mass ejections (CMEs) have all been […]

A New Wind/WAVES Type II Burst Catalog Available Online
by Nat Gopalswamy

2007-11-22

The CDAW Data Center announces the availability of a new catalog of type II radio bursts detected by the Radio and Plasma Waves (WAVES) experiment on board the Wind spacecraft and the associated coronal mass ejections (CMEs) observed by the Solar and Heliospheric Observatory (SOHO). The catalog is available at http://cdaw.gsfc.nasa.gov/CME_list/radio/waves_type2.html The catalog also contains information on the associated flares (X-ray importance and NOAA active region number). The CME sources […]

Radio monitoring of solar activity
by Monique Pick

2007-04-24

We are pleased to announce the opening of a new web site Radio monitoring at http://secchirh.obspm.fr This radio survey is a joint effort of the Paris Observatory, the University of Athens, the University of Ioannina, and the Solar Physics Branch of the Naval Research Laboratory. The site is still under construction. At the present stage, it provides a daily survey (08-16 UT) which includes: Radio spectra covering the 600 MHz-30 […]

A solar type N burst at decametric wavelengths
by Karl-Ludwig Klein

2007-03-12

Electron beams travelling through the solar corona excite Langmuir waves near the local electron plasma frequency. When these Langmuir waves are converted into electromagnetic waves, the radiation can be detected by radio telescopes as bursts with very specific spectral signatures that depend on the magnetic structure which guides the beams. E.g., an electron beam that propagates upward along open magnetic fields produces a short pulse of emission at systematically decreasing […]

Radio-quiet Fast and Wide Coronal Mass Ejections
by Nat Gopalswamy

2007-02-07

Radio-quiet coronal mass ejections (CMEs) are those with no detectable type II radio emission in the metric and decameter-hectometric (DH) wavelengths. (The CMEs may be associated with other types of radio emission such as type III bursts, see definitions for the different types of bursts or the diagram of burst classification). The radio-loud CMEs are those with identifiable type II burst in the DH domain from Wind/WAVES data, irrespective of […]

Are there Radio-quiet Solar Flares?
by Arnold Benz

2007-01-04

Solar flares accelerate particles, and their distribution is usually non-thermal. Non-thermal electrons are prone to velocity space instabilities driving various plasma waves which, in turn, couple into observable radio waves. Such coherent emissions are the result of the combined action of many electrons organized by kinetic plasma waves and can therefore be extremely efficient. Small coherent radio bursts at the limit of present routine observations emit an energy of some […]

High dynamic range solar radio images by combining visibilities from the Giant Meterwave Radio Telescope and the Nancay Radioheliograph
by Claude Mercier

2006-12-07

We present first results from an ongoing program of combining data from the Nancay Radioheliograph NRH and the Giant Meterwave Radio Telescope GMRT, to produce snapshot images of the Sun at meter wavelengths. The data processing includes a superposition of complex visibilities from NRH and GMRT, a Fourier Transform and a cleaning multi-scale algorithm. We show results from a simulation and an observation of a complex noise storm at 327 […]

Particle acceleration during flares – the part played by an outflow termination shock
by Gottfried Mann

2006-10-11

During solar flares energetic nonthermal electromagnetic radiation up to the gamma-ray range is emitted from the solar atmosphere, implying the generation of accelerated electrons and ions. Particle acceleration in cosmic plasma is of fundamental physical interest. The solar corona offers detailed remote sounding of these processes. A fine example An interesting example is the X17-flare of 28 October 2003, one of the strongest events of the last activity cycle. Figure 1 […]