Greifswald 2024 – scientific programme
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EP: Fachverband Extraterrestrische Physik
EP 7: Sun and Heliosphere II
EP 7.2: Talk
Thursday, February 29, 2024, 14:15–14:30, ELP 6: HS 2
Separating fundamental and harmonic emission in LOFAR solar type III radio burst images — •Christian Vocks1, Mario Bisi2, Bartosz Dabrowski3, Diana Morosan4, Peter Gallagher5, Andrzej Krankowski3, Jasmina Magdalenic6, Gottfried Mann1, Christophe Marque6, Barbara Matyjasiak7, Hanna Rothkaehl7, and Pietro Zucca8 — 1Leibniz-Institute for Astrophysics Potsdam (AIP), Germany — 2RAL Space, United Kingdom — 3University of Warmia and Mazury, Olsztyn, Poland — 4University of Helsinki, Finland — 5DIAS, Dublin, Ireland — 6Royal Observatory of Belgium, Brussels, Belgium — 7Polish Academy of Sciences, Warsaw, Poland — 8ASTRON, Dwingeloo, Netherlands
LOFAR spectroscopic imaging observations of solar type III radio bursts during an M class flare show distinct compact sources with variations in their positions and intermittent dual structures. These are interpreted as fundamental and harmonic emission, with the one or other being dominant at times. Sources of fundamental emission at one observed frequency, and harmonic emission from a coronal region with plasma frequency of half the observed frequency, can be clearly separated. Thus, it is possible to yield separate lightcurves, and to compare the flux evolution of fundamental - harmonic pairs, e.g. 35 MHz and 70 MHz. Both fundamental and harmonic emission should originate simultaneously from the same coronal source region. Variations in burst onset times and apparent source position then provide information on transport effects, like scattering and refraction, of radio waves in the solar corona.
Keywords: solar corona; LOFAR; radio burst; solar flare; radio waves