LOFAR tied-array imaging of Type III solar radio bursts

Morosan DE, Gallagher PT, Zucca P, Fallows R, Carley EP, Mann G, Bisi MM, Kerdraon A, Konovalenko AA, Mackinnon AL, Rucker HO, Thide B, Magdalenic J, Vocks C, Reid H, Anderson J, Asgekar A, Avruch OM, Bentum MJ, Bernardi G, Best P, Bonafede A, Bregman I, Breitling F, Broderick J, Brueggen M, Butcher HR, Ciardi B, Conway JE, De Gasperin F, De Geus E, Deller A, Duscha S, Eisloeffel J, Engels D, Falcke H, Ferrari C, Frieswijk W, Garrett MA, Griessmeier J, Gunst AW, Hassall TE, Hessels JWT, Hoeft M, Hoerandel J, Horneffer A, Iacobelli M, Juette E, Karastergiou A, Kondratiev VI, Kramer M, Kuniyoshi M, Kuper G, Maat P, Markoff S, Mckean JP, Mulcahy DD, Munk H, Nelles A, Norden MJ, Orru E, Paas H, Pandey-Pommier M, Pandey VN, Pietka G, Pizzo R, Polatidis AG, Reich W, Roettgering H, Scaife AMM, Schwarz D, Serylak M, Smirnov O, Stappers BW, Stewart A, Tagger M, Tang Y, Tasse C, Thoudam S, Toribio C, Vermeulen R, Van Weeren RJ, Wucknitz O, Yatawatta S, Zarka P (2014)

Publication Status: Published

Publication Type: Journal article

Publication year: 2014

Journal

Publisher: EDP SCIENCES S A

Book Volume: 568

Article Number: ARTN A67

DOI: 10.1051/0004-6361/201423936

Abstract

Context. The Sun is an active source of radio emission which is often associated with energetic phenomena such as solar flares and coronal mass ejections (CMEs). At low radio frequencies (< 100 MHz), the Sun has not been imaged extensively because of the instrumental limitations of previous radio telescopes.Aims. Here, the combined high spatial, spectral, and temporal resolution of the LOw Frequency ARray (LOFAR) was used to study solar Type III radio bursts at 30-90 MHz and their association with CMEs.Methods. The Sun was imaged with 126 simultaneous tied-array beams within <= 5 R-circle dot of the solar centre. This method offers benefits over standard interferometric imaging since each beam produces high temporal (similar to 83 ms) and spectral resolution (12.5 kHz) dynamic spectra at an array of spatial locations centred on the Sun. LOFAR's standard interferometric output is currently limited to one image per second.Results. Over a period of 30 min, multiple Type III radio bursts were observed, a number of which were found to be located at high altitudes (similar to 4 R-circle dot from the solar center at 30 MHz) and to have non-radial trajectories. These bursts occurred at altitudes in excess of values predicted by 1D radial electron density models. The non-radial high altitude Type III bursts were found to be associated with the expanding flank of a CME.Conclusions. The CME may have compressed neighbouring streamer plasma producing larger electron densities at high altitudes, while the non-radial burst trajectories can be explained by the deflection of radial magnetic fields as the CME expanded in the low corona.

Authors with CRIS profile

Involved external institutions

University of Glasgow United Kingdom (GB) Universität Hamburg (UHH) Germany (DE) Netherlands Institute for Radio Astronomy Netherlands (NL) Max-Planck-Institut für Radioastronomie / Max Planck Institute for Radio Astronomy Germany (DE) Radboud University Nijmegen Netherlands (NL) University of Oxford United Kingdom (GB) Thüringer Landessternwarte Tautenburg (TLS) - Karl-Schwarzschild-Observatorium Germany (DE) Harvard University United States (USA) (US) University of Orléans / Université d'Orléans France (FR) Rutherford Appleton Laboratory United Kingdom (GB) Leiden University Netherlands (NL) Leibniz Institute for Astrophysics Potsdam / Leibniz-Institut für Astrophysik Potsdam Germany (DE) Chalmers University of Technology / Chalmers tekniska högskola Sweden (SE) PSL Research University / Université de recherche Paris Sciences et Lettres France (FR) Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. (MPG) / Max Planck Society for the Advancement of Science Germany (DE) Österreichische Akademie der Wissenschaften Austria (AT) University of Southampton United Kingdom (GB) University of Edinburgh United Kingdom (GB) Australian National University (ANU) Australia (AU) University of Nice Sophia Antipolis / Université Nice Sophia Antipolis France (FR) Trinity College Dublin Ireland (IE) Ruhr-Universität Bochum (RUB) Germany (DE) Universität Bielefeld Germany (DE) Rhodes University South Africa (ZA) University of Groningen / Rijksuniversiteit Groningen Netherlands (NL) University of Manchester United Kingdom (GB) Netherlands Institute for Space Research / Stichting Ruimteonderzoek Nederland (SRON) Netherlands (NL) University of Amsterdam Netherlands (NL) Observatoire de Lyon France (FR) Royal Observatory of Belgium / Koninklijke Sterrenwacht van België / Observatoire royal de Belgique Belgium (BE) The Swedish Institute of Space Physics Sweden (SE)

How to cite

APA:

Morosan, D.E., Gallagher, P.T., Zucca, P., Fallows, R., Carley, E.P., Mann, G.,... Zarka, P. (2014). LOFAR tied-array imaging of Type III solar radio bursts. Astronomy & Astrophysics, 568. https://dx.doi.org/10.1051/0004-6361/201423936

MLA:

Morosan, D. E., et al. "LOFAR tied-array imaging of Type III solar radio bursts." Astronomy & Astrophysics 568 (2014).

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