Hercules A

Hercules A
Radio-Optical View of the Galaxy Hercules A - Many thanks to: NASA, ESA, S. Baum and C. O'Dea (RIT), R. Perley and W. Cotton (NRAO/AUI/NSF), and the Hubble Heritage Team (STScI/AURA)

Friday, November 9, 2012

LOFAR images and spectra of type III bursts, in the 122 to 162 MHz band, on 111013

I review the ASTRON (Netherlands Institute for Radio Astronomy) and JIVE (Joint Institute for VLBI in Europe) Daily Image for 121031:

by Gottfried Mann, Christian Vocks, and Frank Breitling.

 "...On October 13, 2011 the Sun was observed by LOFAR in the framework of its key science project "Solar Physics and Space Weather with LOFAR". The results are presented on this slide:

At the bottom the dynamic radio spectrum is shown in the frequency range of 122 - 162 MHz. It shows four so-called type III radio bursts. They appear as stripes of enhanced radio emission rapidly drifting from high to low frequencies. They are signatures of beams of energetic electrons generated by a flare on the Sun. If they travel along open magnetic field lines through the corona, they excite along their path radio radiation manifesting as type III bursts.

On top the corresponding radio images at 133 MHz are show before (left), during (middle), and after (right) the occurrence of the type III burst at 10:27:18 UT. The white circle indicates the limb of the visible disc of the Sun.

The radio images are produced by means of the solar imaging pipeline developed at the Leibniz-Institut fur Astrophysik Potsdam (AIP). The brightening of the radio source during the type III burst is seen at the South-East limb of the Sun. This observation impressively demonstrates that LOFAR can really work as a dynamic spectroscopic radio imager of the Sun..."