First imaging spectroscopy observations of solar drift pair bursts
TLDR
In this article, the authors reported unique observations of a cluster of drift pair bursts in the frequency range of 30−70 MHz made on 12 July 2017 using the Low Frequency Array (LOFAR).Abstract:
Drift pairs are an unusual and puzzling type of fine structure sometimes observed in dynamic spectra of solar radio emission. They appear as two identical short narrowband drifting stripes separated in time; both positive and negative frequency drifts are observed. Currently, due to the lack of imaging observations, there is no satisfactory explanation for this phenomenon. Using the Low Frequency Array (LOFAR), we report unique observations of a cluster of drift pair bursts in the frequency range of 30−70 MHz made on 12 July 2017. Spectral imaging capabilities of the instrument have allowed us for the first time to resolve the temporal and frequency evolution of the source locations and sizes at a fixed frequency and along the drifting pair components. Sources of two components of a drift pair have been imaged and found to propagate in the same direction along nearly the same trajectories. Motion of the second component source is seen to be delayed in time with respect to that of the first one. The source trajectories can be complicated and non-radial; positive and negative frequency drifts correspond to opposite propagation directions. The drift pair bursts with positive and negative frequency drifts, as well as the associated broadband type-III-like bursts, are produced in the same regions. The visible source velocities are variable from zero to a few 104 (up to ∼105 ) km s−1 , which often exceeds the velocities inferred from the drift rate (∼104 km s−1 ). The visible source sizes are of about 10′−18′; they are more compact than typical type III sources at the same frequencies. The existing models of drift pair bursts cannot adequately explain the observed features. We discuss the key issues that need to be addressed, and in particular the anisotropic scattering of the radio waves. The broadband bursts observed simultaneously with the drift pairs differ in some aspects from common type III bursts and may represent a separate type of emission.read more
Citations
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Parametric Simulation Studies on the Wave Propagation of Solar Radio Emission: The Source Size, Duration, and Position
TL;DR: In this article, the variation of the apparent source size, burst duration, and source position of both fundamental emission and harmonic emission at frequency 35 MHz are simulated as the function of the anisotropic parameter and angular scattering rate coefficient.
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Subsecond Time Evolution of Type III Solar Radio Burst Sources at Fundamental and Harmonic Frequencies
Xingyao Chen,Xingyao Chen,Eduard P. Kontar,Nicolina Chrysaphi,Natasha L. S. Jeffrey,Mykola Gordovskyy,Yihua Yan,Baolin Tan +7 more
TL;DR: In this paper, 3D Monte Carlo ray-tracing simulations were used to explain the image dynamics at the fundamental (near plasma frequency) and harmonic (double) plasma emissions observed at ∼32 MHz.
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Radio Echo in the Turbulent Corona and Simulations of Solar Drift-pair Radio Bursts
TL;DR: In this paper, the drift-pair parameters are qualitatively analyzed and compared with the newly developed Monte Carlo ray-tracing technique simulating radio-wave propagation in the inhomogeneous anisotropic turbulent solar corona.
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First Frequency-Time-Resolved Imaging Spectroscopy Observations of Solar Radio Spikes
TL;DR: In this paper, the authors present spatially, frequency and time resolved observations of individual radio spikes associated with a coronal mass ejection (CME) and demonstrate that the observed area is increasing in time and the centroid positions of individual spikes move superluminally parallel to the solar limb.
Journal ArticleDOI
Sub-second time evolution of Type III solar radio burst sources at fundamental and harmonic frequencies
Xingyao Chen,Eduard P. Kontar,Nicolina Chrysaphi,Natasha L. S. Jeffrey,Mykola Gordovskyy,Yihua Yan,Baolin Tan +6 more
TL;DR: In this article, 3D Monte Carlo ray-tracing simulations were used to explain the anisotropic density turbulence in the inhomogeneous solar corona to quantitatively explain the image dynamics at the fundamental (near plasma frequency) and harmonic (double) plasma emissions observed at \sim 32~MHz.
References
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LOFAR: The LOw-Frequency ARray
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TL;DR: In dit artikel zullen the authors LOFAR beschrijven: van de astronomische mogelijkheden met de nieuwe telescoop tot aan een nadere technische beshrijving of het instrument.
Journal ArticleDOI
LOFAR: The LOw-Frequency ARray
M. P. van Haarlem,Michael W. Wise,A. W. Gunst,George Heald,John McKean,Jason W. T. Hessels,A. G. de Bruyn,R. Nijboer,John D. Swinbank,Richard Fallows,Michiel A. Brentjens,A. Nelles,Rainer Beck,Heino Falcke,Rob Fender,Jörg R. Hörandel,Léon V. E. Koopmans,G. Mann,George K. Miley,Huub Röttgering,B. W. Stappers,Ralph A. M. J. Wijers,Saleem Zaroubi,M. van den Akker,A. Alexov,James M. Anderson,Kenneth C. Anderson,A. van Ardenne,Michel Arts,Ashish Asgekar,I. M. Avruch,F. Batejat,L. Bähren,Martin Bell,Michael R. Bell,I. van Bemmel,P. Bennema,Mark J. Bentum,Gianni Bernardi,P. N. Best,Laura Birzan,Annalisa Bonafede,Albert-Jan Boonstra,Robert Braun,Joel N. Bregman,F. Breitling,R. H. van de Brink,J. W. Broderick,P. C. Broekema,W. N. Brouw,Marcus Brüggen,Harvey Butcher,W. A. van Cappellen,B. Ciardi,T. Coenen,John Conway,A. H. W. M. Coolen,Arthur Corstanje,S. Damstra,O. Davies,Adam Deller,R. J. Dettmar,G. van Diepen,K. Dijkstra,P. Donker,A. Doorduin,J. Dromer,M. Drost,A. van Duin,Jochen Eislöffel,J. van Enst,Chiara Ferrari,Wilfred Frieswijk,H. Gankema,M. A. Garrett,F. de Gasperin,M. Gerbers,E. de Geus,J.-M. Grießmeier,T. Grit,P. Gruppen,J. P. Hamaker,Tim Hassall,Matthias Hoeft,H. A. Holties,A. Horneffer,A. J. van der Horst,A. van Houwelingen,A. Huijgen,Marco Iacobelli,Hubertus Intema,N. J. Jackson,Vibor Jelić,A. de Jong,E. Juette,D. Kant,Aris Karastergiou,A. Koers,H. Kollen,V. I. Kondratiev,E. Kooistra,Y. Koopman,A. Koster,M. Kuniyoshi,Michael Kramer,Gerard H. Kuper,P. Lambropoulos,Casey J. Law,J. van Leeuwen,J. Lemaitre,M. Loose,P. Maat,Giulia Macario,Sera Markoff,J. Masters,D. McKay-Bukowski,H. Meijering,H. Meulman,Maaijke Mevius,Enno Middelberg,R. Millenaar,James Miller-Jones,R. N. Mohan,J. D. Mol,J. Morawietz,Raffaella Morganti,D. D. Mulcahy,E. Mulder,H. Munk,Lambert J.M. Nieuwenhuis,R.V. van Nieuwpoort,J. E. Noordam,M. J. Norden,A. Noutsos,A. R. Offringa,Hans Olofsson,Amitesh Omar,Emanuela Orrú,R. Overeem,H. Paas,M. Pandey-Pommier,Vishambhar Pandey,Roberto Pizzo,A. G. Polatidis,D. A. Rafferty,Steve Rawlings,W. Reich,J.-P. de Reijer,J. Reitsma,A. Renting,P. Riemers,E. Rol,J. W. Romein,J. Roosjen,M. Ruiter,Anna M. M. Scaife,K. van der Schaaf,B. Scheers,Pim Schellart,A. P. Schoenmakers,G. Schoonderbeek,M. Serylak,Aleksandar Shulevski,J. Sluman,Oleg Smirnov,Charlotte Sobey,H. Spreeuw,Matthias Steinmetz,C. G. M. Sterks,H.-J. Stiepel,K. Stuurwold,Michel Tagger,Y. Tang,C. Tasse,I. Thomas,Satyendra Thoudam,M. C. Toribio,B. van der Tol,O. Usov,M. van Veelen,A. van Veen,S. ter Veen,Joris P. W. Verbiest,R. Vermeulen,N. J. Vermaas,C. Vocks,C. Vogt,M. de Vos,E. van der Wal,R. J. van Weeren,H. Weggemans,Patrick Weltevrede,Simon D. M. White,Stefan J. Wijnholds,T. Wilhelmsson,Olaf Wucknitz,Sarod Yatawatta,P. Zarka,Anton Zensus,J. E. van Zwieten +199 more
TL;DR: The International LOFAR Telescope (ILT) as mentioned in this paper is a new-generation radio interferometer constructed in the north of the Netherlands and across europe, which covers the largely unexplored low frequency range from 10-240 MHz and provides a number of unique observing capabilities.
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The Solar Corona in Active Regions and the Thermal Origin of the Slowly Varying Component of Solar Radio Radiation.
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Solar wind density model from km-wave type III bursts
Hector Alvarez,F. T. Haddock +1 more
TL;DR: In this paper, the analysis of type III bursts observed from the OGO-5 satellite between 3.5 MHz and 50 kHz (λ6 km) gives an empirical expression for the frequency drift rate as a function of frequency that is valid from 75 kHz to 550 MHz.
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Imaging spectroscopy of solar radio burst fine structures.
Eduard P. Kontar,Sijie Yu,Alexey A. Kuznetsov,A. G. Emslie,B. Alcock,Natasha L. S. Jeffrey,Valentin Melnik,Nicolas Bian,Prasad Subramanian +8 more
TL;DR: Radio observations of the solar atmosphere provide a unique view on the non-thermal processes in the outer atmosphere and the authors use LOFAR observations to demonstrate that the observed radio burst characteristics are dominated by propagation effects rather than underlying emission variations.