Interferometric Imaging with LOFAR Remote Baselines of the Fine Structures of a Solar Type IIIb Radio Burst

Abstract

Context. Solar radio bursts originate mainly from high energy electrons accelerated in solar eruptions like solar flares, jets, and coronal mass ejections. A subcategory of solar radio bursts with short time duration may be used as a proxy to understand the wave generation and propagation within the corona. Aims. Complete case studies of the source size, position and kinematics of short term bursts are very rare due to instrumental limitations. A comprehensive multi-frequency spectroscopic and imaging study was carried out of a clear example of a solar type IIIb-III pair. Methods. In this work, the source of the radio burst was imaged with the interferometric mode, using the remote baselines of the LOw Frequency ARray (LOFAR). A detailed analysis of the fine structures in the spectrum and of the radio source motion with imaging was conducted. Results. The study shows how the fundamental and harmonic components have a significantly different source motion. The apparent source of the fundamental emission at 26.56MHz displaces away from the solar disk center at about 4 times the speed of light, while the apparent source of the harmonic emission at the same frequency shows a speed of < 0.02c. The source size of the harmonic emission, observed in this case, is smaller than that in previous studies, indicating the importance of the use of the remote baselines.

References in corpus (5)

• Astrophysics Source Code Library
• WSClean: an implementation of a fast, generic wide-field imager for radio astronomy
• A Review of Solar Type III Radio Bursts
• An optimized algorithm for multi-scale wideband deconvolution of radio astronomical images
• Dynamics of electron beams in the solar corona plasma with density fluctuations

Cited by in corpus (10)

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• Structured type III radio bursts observed in interplanetary space
• Parametric simulation studies on the wave propagation of solar radio emission: the source size, duration, and position
• First Results from the REAL-time Transient Acquisition backend (REALTA) at the Irish LOFAR station
• Solar Radio Spikes and Type IIIb Striae Manifestations of Sub-second Electron Acceleration Triggered by a Coronal Mass Ejection
• Solar observations with single-dish INAF radio telescopes: continuum imaging in the 18-26 GHz range
• LOFAR imaging of the solar corona during the 2015 March 20 solar eclipse
• Interferometric imaging of the type IIIb and U radio bursts observed with LOFAR on 22 August 2017
• Interferometric imaging, and beam-formed study of a moving Type IV Radio burst with LOFAR