Solar Physics

, Volume 284, Issue 2, pp 541-558

First online:

A Burst with Double Radio Spectrum Observed up to 212 GHz

  • C. G. Giménez de CastroAffiliated withCRAAM, Universidade Presbiteriana MackenzieInstituto de Astronomía y Física del Espacio, CONICET-UBA Email author 
  • , G. D. CristianiAffiliated withInstituto de Astronomía y Física del Espacio, CONICET-UBAFacultad de Ciencias Exactas y Naturales, FCEN-UBA
  • , P. J. A. SimõesAffiliated withSchool of Physics & Astronomy, University of Glasgow
  • , C. H. MandriniAffiliated withInstituto de Astronomía y Física del Espacio, CONICET-UBAFacultad de Ciencias Exactas y Naturales, FCEN-UBA
  • , E. CorreiaAffiliated withCRAAM, Universidade Presbiteriana MackenzieInstituto Nacional de Pesquisas Espaciais
  • , P. KaufmannAffiliated withCRAAM, Universidade Presbiteriana MackenzieCentro de Componentes Semicondutores, Universidade Estadual de Campinas

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access


We study a solar flare that occurred on 10 September 2002, in active region NOAA 10105, starting around 14:52 UT and lasting approximately 5 minutes in the radio range. The event was classified as M2.9 in X-rays and 1N in Hα. Solar Submillimeter Telescope observations, in addition to microwave data, give a good spectral coverage between 1.415 and 212 GHz. We combine these data with ultraviolet images, hard and soft X-ray observations, and full-disk magnetograms. Images obtained from Ramaty High Energy Solar Spectroscopic Imager data are used to identify the locations of X-ray sources at different energies, and to determine the X-ray spectrum, while ultraviolet images allow us to characterize the coronal flaring region. The magnetic field evolution of the active region is analyzed using Michelson Doppler Imager magnetograms. The burst is detected at all available radio frequencies. X-ray images (between 12 keV and 300 keV) reveal two compact sources. In the 212 GHz data, which are used to estimate the radio-source position, a single compact source is seen, displaced by 25″ from one of the hard X-ray footpoints. We model the radio spectra using two homogeneous sources, and we combine this analysis with that of hard X-rays to understand the dynamics of the accelerated particles. Relativistic particles, observed at radio wavelengths above 50 GHz, have an electron index evolving with the typical soft–hard–soft behavior.


Radio bursts, association with flares Radio bursts, microwave X-ray bursts, association with flares Flares, relation to magnetic field Chromosphere, active