LOFAR tied-array imaging of Type III solar radio bursts
Journal article, 2014
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.
spacecraft
shock
density
radioheliograph
corona
acceleration
electrons
waves
plasma emission
Author
D. E. Morosan
Trinity College Dublin
P. T. Gallagher
Trinity College Dublin
P. Zucca
Trinity College Dublin
R. A. Fallows
Netherlands Institute for Radio Astronomy (ASTRON)
E. P. Carley
Trinity College Dublin
G. Mann
Leibniz Institute for Astrophysics Potsdam
M. M. Bisi
STFC Rutherford Appleton Laboratory
A. Kerdraon
Observatoire de Paris-Meudon
A. A. Konovalenko
National Academy of Sciences in Ukraine
A. L. MacKinnon
University of Glasgow
H. O. Rucker
Osterreichische Akademie Der Wissenschaften
B. Thide
The Swedish Institute of Space Physics
J. Magdalenic
Royal Observatory of Belgium
C. Vocks
Leibniz Institute for Astrophysics Potsdam
H. Reid
University of Glasgow
J. Anderson
Leibniz Institute for Astrophysics Potsdam
A. Asgekar
Shell Technology Center
Netherlands Institute for Radio Astronomy (ASTRON)
I.M. Avruch
University of Groningen
Netherlands Institute for Space Research (SRON)
M. J. Bentum
Netherlands Institute for Radio Astronomy (ASTRON)
G. Bernardi
Harvard-Smithsonian Center for Astrophysics
P. Best
University of Edinburgh
A. Bonafede
University of Hamburg
I. Bregman
Netherlands Institute for Radio Astronomy (ASTRON)
F. Breitling
Leibniz Institute for Astrophysics Potsdam
J. Broderick
University of Southampton
M. Brueggen
University of Hamburg
H. R. Butcher
Australian National University
B. Ciardi
Max Planck Society
John Conway
Chalmers, Earth and Space Sciences, Onsala Space Observatory
F. De Gasperin
University of Hamburg
E. de Geus
Netherlands Institute for Radio Astronomy (ASTRON)
A. Deller
Netherlands Institute for Radio Astronomy (ASTRON)
S. Duscha
Netherlands Institute for Radio Astronomy (ASTRON)
J. Eislöffel
D. Engels
University of Hamburg
H. Falcke
Netherlands Institute for Radio Astronomy (ASTRON)
Radboud University
C. Ferrari
Université Nice Sophia Antipolis (UNS)
W. Frieswijk
Netherlands Institute for Radio Astronomy (ASTRON)
M. A. Garrett
Netherlands Institute for Radio Astronomy (ASTRON)
Leiden University
J. Griessmeier
University of Orléans
A. W. Gunst
Netherlands Institute for Radio Astronomy (ASTRON)
T. E. Hassall
University of Southampton
University of Manchester
J. W. T. Hessels
Anton Pannekoek Institute for Astronomy
Netherlands Institute for Radio Astronomy (ASTRON)
M. Hoeft
J.R. Hörandel
Radboud University
A. Horneffer
Max Planck Society
M. Iacobelli
Leiden University
E. Juette
Ruhr-Universität Bochum
A. Karastergiou
University of Oxford
V. I. Kondratiev
Netherlands Institute for Radio Astronomy (ASTRON)
Russian Academy of Sciences
M. Kramer
University of Manchester
Max Planck Society
M. Kuniyoshi
Max Planck Society
G. Kuper
Netherlands Institute for Radio Astronomy (ASTRON)
P. Maat
Netherlands Institute for Radio Astronomy (ASTRON)
S. Markoff
Anton Pannekoek Institute for Astronomy
J. P. McKean
University of Groningen
Netherlands Institute for Radio Astronomy (ASTRON)
D. D. Mulcahy
Max Planck Society
H. Munk
Netherlands Institute for Radio Astronomy (ASTRON)
A. Nelles
Radboud University
M. J. Norden
Netherlands Institute for Radio Astronomy (ASTRON)
E. Orru
Netherlands Institute for Radio Astronomy (ASTRON)
H. Paas
University of Groningen
M. Pandey-Pommier
Lyon Observatory
V. N. Pandey
Netherlands Institute for Radio Astronomy (ASTRON)
G. Pietka
University of Oxford
R. Pizzo
Netherlands Institute for Radio Astronomy (ASTRON)
A. G. Polatidis
Netherlands Institute for Radio Astronomy (ASTRON)
W. Reich
Max Planck Society
H. Rottgering
Leiden University
A. M. M. Scaife
University of Southampton
D. Schwarz
Bielefeld University
M. Serylak
University of Oxford
O. Smirnov
Rhodes University
B. W. Stappers
University of Manchester
A. Stewart
University of Oxford
M. Tagger
University of Orléans
Y. Tang
Netherlands Institute for Radio Astronomy (ASTRON)
C. Tasse
Observatoire de Paris-Meudon
S. Thoudam
Radboud University
C. Toribio
Netherlands Institute for Radio Astronomy (ASTRON)
R. Vermeulen
Netherlands Institute for Radio Astronomy (ASTRON)
R. J. van Weeren
Harvard-Smithsonian Center for Astrophysics
O. Wucknitz
University of Bonn
Max Planck Society
S. Yatawatta
Netherlands Institute for Radio Astronomy (ASTRON)
P. Zarka
Observatoire de Paris-Meudon
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 568 articl no. A67- A67Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201423936