Millisecond radio spikes

Benz, A. O.

doi:10.1007/bf00159950

Cited by 215 publications

(98 citation statements)

References 22 publications

(4 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…by Raulin et al (1994) to be accompanied by a delayed continuum radio emission and a soft X-ray brightening. The similarity of spikes and type I bursts has been emphasized previously (Benz 1985). Both noise storms and metric spike/type III bursts are not associated with regular, hard X-ray and centimeter-wave Send offprint requests to: A. O. Benz, e-mail: benz@astro.phys.ethz.ch emitting flares.…”

Section: Introductionmentioning

confidence: 68%

“…They may be indicative of post-flare high-corona acceleration sites. Narrowband spikes at decimetric frequencies have been reported in the flare rise phase and main phase, even at low frequencies (Benz 1985). It will be interesting to investigate the above findings on the location of spikes earlier in the flare and at higher decimetric frequencies.…”

Section: Discussionmentioning

confidence: 89%

See 1 more Smart Citation

Location of narrowband spikes in solar flares

Benz

Saint-Hilaire²,

Vilmer³

2002

A&A

Self Cite

View full text Add to dashboard Cite

Abstract. Narrowband spikes of the decimeter type have been identified in dynamic spectrograms of Phoenix-2 of ETH Zurich and located in position with the Nançay Radioheliograph at the same frequency. The spike positions have been compared with the location of hard X-ray emission and the thermal flare plasma in soft X-rays and EUV lines. The decimetric spikes are found to be single sources located some 20 to 400 away from the flare site in hard or soft X-rays. In most cases there is no bright footpoint nearby. In at least two cases the spikes are near loop tops. These observations do not confirm the widely held view that the spike emission is produced by some loss-cone instability masering near the footpoints of flare loops. On the other hand, the large distance to the flare sites and the fact that these spikes are all observed in the flare decay phase make the analyzed spike sources questionable sites for the main flare electron acceleration. They possibly indicate coronal post-flare acceleration sites.

show abstract

Section: Introductionmentioning

confidence: 68%

Section: Discussionmentioning

confidence: 89%

Location of narrowband spikes in solar flares

Benz

Saint-Hilaire²,

Vilmer³

2002

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…Transverse structure in the corona is therefore very important for the delivery of wave energy to the chromosphere, with the length scale of focused fast waves determined by the footpoint size of the waveguide. Observational studies of radio and HXR emission from flares show a spectrum of time scales from milliseconds to tens of minutes, from which it has been suggested that flares are composed of elementary flare bursts having durations in the range 1−25 s (van Beek et al 1974;de Jager & de Jonge 1978), and energy release fragments in the range 50−1000 ms (Kiplinger et al 1983;Benz 1985Benz , 1986Machado et al 1993), with longer time scales attributable to pileup of shorter events. In this context, the driver in our simulations represents the injection of a fundamental element by the energy release, from which a general picture of wave transport is obtained by considering many such bursts with varying durations, superimposed in a chain lasting up to several minutes.…”

Section: Discussionmentioning

confidence: 99%

Solar flares and focused energy transport by MHD waves

Russell

Stackhouse

2013

A&A

View full text Add to dashboard Cite

Context. Transport of flare energy from the corona to the chromosphere has traditionally been assigned to electron beams; however, interest has recently been renewed in magnetohydrodynamic (MHD) waves as a complementary or alternative mechanism. Aims. We determine whether, and under what conditions, MHD waves deliver spatially localised energy to the chromosphere, as required if MHD waves are to contribute to emission from flare ribbons and kernels. This paper also highlights several properties of MHD waves that are relevant to solar flares and demonstrates their application to the flare problem. Methods. Transport is investigated using a magnetic arcade model and 2.5D MHD simulations. Different wave polarisations are considered and the effect of fine structuring transverse to the magnetic field is also examined. Ray tracing provides additional insight into the evolution of waveguided fast waves. Results. Alfvén waves are very effective at delivering energy fluxes to small areas of chromosphere, localisation being enhanced by magnetic field convergence and phase mixing. Fast waves, in the absence of fine coronal structure, are more suited to powering emission from diffuse rather than compact sources; however, fast waves can be strongly localised by coronal waveguides, in which case focused energy is best transported to the chromosphere when waveguides are directly excited by the energy release. Conclusions. MHD waves pass an important test for inclusion in future flare models.

show abstract

“…The radio narrowband decimetric spikes belong to the most interesting radio bursts with exceptionally high brightness temperatures (T b ≈ 10 15 K) and short durations (≤0.1 s, see the review by Benz 1986). Their observational characteristics have been described in many papers (e.g.…”

Section: Introductionmentioning

confidence: 99%

Magnetoacoustic waves in the narrowband dm-spikes sources

Karlický

Jelínek

Mészárosová

2011

A&A

View full text Add to dashboard Cite

Aims.A new type of analysis of the narrowband dm-spikes in solar radio radiation is introduced to look for magnetoacoustic waves in their sources. Methods. The Fourier and wavelet methods were used. For the first time, the tadpole structures in the wavelet spectra of this radio emission were searched for. Results. Fifteen groups of the narrowband dm-spikes, observed during solar flares, were selected and analyzed by the Fourier and wavelet analysis methods. We found that the mean Fourier spectra of these spikes in frequency space are the powerlaws with a powerlaw index in the range −1.2 -−1.8. Furthermore, their wavelet spectra based on time series reveal tadpoles at some frequencies, which indicates the presence of magnetoacoustic waves. These waves are interpreted as propagating through a source of the narrowband dm-spikes. It is proposed that the spikes are generated by driven coalescence and fragmentation processes in turbulent reconnection outflow. This interpretation is supported by a simultaneous observation of drifting pulsating structures (DPSs) and spikes. Finally, modeling of the magnetoacoustic waves and tadpoles in the Harris current sheet supports this interpretation.

show abstract

Millisecond radio spikes

Cited by 215 publications

References 22 publications

Location of narrowband spikes in solar flares

Location of narrowband spikes in solar flares

Solar flares and focused energy transport by MHD waves

Magnetoacoustic waves in the narrowband dm-spikes sources

Contact Info

Product

Resources

About