LOFAR tied-array imaging of Type III solar radio bursts
Artikel i vetenskaplig tidskrift, 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.

corona

radioheliograph

waves

plasma emission

density

electrons

spacecraft

shock

acceleration

Författare

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

Astrophysikalisches Institut Potsdam

M. M. Bisi

Rutherford Appleton Laboratory

A. Kerdraon

GEPI - Galaxies, Etoiles, Physique, Instrumentation

A. A. Konovalenko

Institute of Radio Astronomy National Academy of Sciences of Ukraine

A. L. MacKinnon

University of Glasgow

H. O. Rucker

Osterreichische Akademie Der Wissenschaften

B. Thide

Instiutet for rymdfysik

J. Magdalenic

Royal Observatory of Belgium

C. Vocks

Astrophysikalisches Institut Potsdam

H. Reid

University of Glasgow

J. Anderson

Astrophysikalisches Institut Potsdam

A. Asgekar

Shell Technology Center

Netherlands Institute for Radio Astronomy (ASTRON)

I.M. Avruch

Netherlands Institute for Space Research (SRON)

Rijksuniversiteit Groningen

M. J. Bentum

Netherlands Institute for Radio Astronomy (ASTRON)

G. Bernardi

Harvard-Smithsonian Center for Astrophysics

P. Best

University of Edinburgh

A. Bonafede

Universität Hamburg

I. Bregman

Netherlands Institute for Radio Astronomy (ASTRON)

F. Breitling

Astrophysikalisches Institut Potsdam

J. Broderick

University of Southampton

M. Brueggen

Universität Hamburg

H. R. Butcher

Australian National University

B. Ciardi

Max Planck-institutet

John Conway

Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium

F. De Gasperin

Universität 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

Universität Hamburg

H. Falcke

Radboud Universiteit

Netherlands Institute for Radio Astronomy (ASTRON)

C. Ferrari

Université Nice Sophia Antipolis (UNS)

W. Frieswijk

Netherlands Institute for Radio Astronomy (ASTRON)

M. A. Garrett

Netherlands Institute for Radio Astronomy (ASTRON)

Universiteit Leiden

J. Griessmeier

Universite d'Orleans

A. W. Gunst

Netherlands Institute for Radio Astronomy (ASTRON)

T. E. Hassall

University of Southampton

University of Manchester

J. W. T. Hessels

Netherlands Institute for Radio Astronomy (ASTRON)

Anton Pannekoek Institute for Astronomy

M. Hoeft

J.R. Hörandel

Radboud Universiteit

A. Horneffer

Max Planck-institutet

M. Iacobelli

Universiteit Leiden

E. Juette

Ruhr-Universität Bochum

A. Karastergiou

University of Oxford

V. I. Kondratiev

Russian Academy of Sciences

Netherlands Institute for Radio Astronomy (ASTRON)

M. Kramer

Max Planck-institutet

University of Manchester

M. Kuniyoshi

Max Planck-institutet

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

Netherlands Institute for Radio Astronomy (ASTRON)

Rijksuniversiteit Groningen

D. D. Mulcahy

Max Planck-institutet

H. Munk

Netherlands Institute for Radio Astronomy (ASTRON)

A. Nelles

Radboud Universiteit

M. J. Norden

Netherlands Institute for Radio Astronomy (ASTRON)

E. Orru

Netherlands Institute for Radio Astronomy (ASTRON)

H. Paas

Rijksuniversiteit Groningen

M. Pandey-Pommier

Observatoire de Lyon

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-institutet

H. Rottgering

Universiteit Leiden

A. M. M. Scaife

University of Southampton

D. Schwarz

Universität Bielefeld

M. Serylak

University of Oxford

O. Smirnov

Rhodes University

B. W. Stappers

University of Manchester

A. Stewart

University of Oxford

M. Tagger

Universite d'Orleans

Y. Tang

Netherlands Institute for Radio Astronomy (ASTRON)

C. Tasse

GEPI - Galaxies, Etoiles, Physique, Instrumentation

S. Thoudam

Radboud Universiteit

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

Universität Bonn

Max Planck-institutet

S. Yatawatta

Netherlands Institute for Radio Astronomy (ASTRON)

P. Zarka

GEPI - Galaxies, Etoiles, Physique, Instrumentation

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 568 articl no. A67- A67

Ämneskategorier

Astronomi, astrofysik och kosmologi

DOI

10.1051/0004-6361/201423936