Solar Decameter Spikes

Melnik, V. N.; Shevchuk, N. V.; Konovalenko, A. A.; Rücker, H. O.; Dorovskyy, V. V.; Poedts, Stefaan; Lecacheux, A.

doi:10.1007/s11207-013-0434-1

Cited by 33 publications

(54 citation statements)

References 16 publications

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“…In Fig. 6a we plot data from Table 1 of Dabrowski et al (2011), together with our results and those of Melnik et al (2011Melnik et al ( , 2014; the curve is a power law with α = 1.32, which is the average of the power reported by Guedel & Benz (1990;α = 1.34) and by Mészárosová et al (2003) and Rozhansky et al (2008;α = 1.29). This plot indicates a reasonable power law fit up to ∼2 GHz.…”

Section: Duration and Bandwidth Of Individual Burstsmentioning

confidence: 77%

High resolution observations with Artemis-IV and the NRH

Bouratzis

Hillaris

Alissandrakis

et al. 2016

A&A

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Context. Narrow-band bursts appear on dynamic spectra from microwave to decametric frequencies as fine structures with very small duration and bandwidth. They are believed to be manifestations of small scale energy release through magnetic reconnection. Aims. We analyzed 27 metric type IV events with embedded narrow-band bursts, which were observed by the ARTEMIS-IV radio spectrograph from 30 June 1999 to 1 August 2010. We examined the morphological characteristics of isolated narrow-band structures (mostly spikes) and groups or chains of structures. Methods. The events were recorded with the SAO high resolution (10 ms cadence) receiver of ARTEMIS-IV in the 270-450 MHz range. We measured the duration, spectral width, and frequency drift of ∼12 000 individual narrow-band bursts, groups, and chains. Spike sources were imaged with the Nançay radioheliograph (NRH) for the event of 21 April 2003. Results. The mean duration of individual bursts at fixed frequency was ∼100 ms, while the instantaneous relative bandwidth was ∼2%. Some bursts had measurable frequency drift, either positive or negative. Quite often spikes appeared in chains, which were closely spaced in time (column chains) or in frequency (row chains). Column chains had frequency drifts similar to type-IIId bursts, while most of the row chains exhibited negative frequently drifts with a rate close to that of fiber bursts. From the analysis of NRH data, we found that spikes were superimposed on a larger, slowly varying, background component. They were polarized in the same sense as the background source, with a slightly higher degree of polarization of ∼65%, and their size was about 60% of their size in total intensity. Conclusions. The duration and bandwidth distributions did not show any clear separation in groups. Some chains tended to assume the form of zebra, lace stripes, fiber bursts, or bursts of the type-III family, suggesting that such bursts might be resolved in spikes when viewed with high resolution. The NRH data indicate that the spikes are not fluctuations of the background, but represent additional emission such as what would be expected from small-scale reconnection.

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Section: Duration and Bandwidth Of Individual Burstsmentioning

confidence: 77%

High resolution observations with Artemis-IV and the NRH

Bouratzis

Hillaris

Alissandrakis

et al. 2016

A&A

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“…The extreme values were equal to 1608 MHz s −1 and 776 MHz s −1 (Dabrowski, Rudawy, and Karlický, 2011), respectively; • the spike fluxes in most cases are not higher than 100 s.f.u. (where 1 s.f.u = 10 −22 W m −2 Hz −1 ) (Benz et al, 1992;Melnik et al, 2014). The maximum value of spike flux registered in the decameter range was equal about 200 s.f.u.…”

Section: Introductionmentioning

confidence: 98%

“…The maximum value of spike flux registered in the decameter range was equal about 200 s.f.u. (Melnik et al, 2014). The brightness temperatures of spikes can reach 10 12 -10 15 K, which points to a non-thermal mechanism of radiation (Messerotti, Nonino, and Zlobec, 1985;Benz, 1986); • the polarization of the spikes in most cases is circular and varies from 0 to 100 % (Markeev and Chernov, 1970;Barrow and Saunders, 1972;Benz, Csillaghy, and Aschwanden, 1996).…”

Section: Introductionmentioning

confidence: 99%

“…The average value is only 25 % (Benz, 1986); • two mechanisms of spike generation are considered: the electron-cyclotron maser mechanism and the plasma mechanism. The electron-cyclotron maser mechanism is considered to describe high-frequency spikes (Benz et al, 1992;Fleishman and Mel'nikov, 1998), while the plasma mechanism is involved to describe low-frequency ones (Warwick and Dulk, 1969;Baselian et al, 1974;Stewart, 1975;Zhelezniakov and Zaitsev, 1975;de La Noe, 1975;Melnik et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…Following Melnik et al (2014), the decameter bursts with the short durations of about one second and narrow frequency bandwidths 50 -70 kHz chaotically located on the dynamical spectrum we call decameter spikes (Figure 1). These morphological properties of the spikes make their identification simple and confident.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The Storm of Decameter Spikes During the Event of 14 June 2012

et al. 2015

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An event on 14 June 2012, observed with the radio telescopes UTR-2 (Kharkov, Ukraine), URAN-2 (Poltava, Ukraine), and NDA (Nançay, France) during a joint Summer campaign, is analyzed and discussed. The high solar activity resulted in a storm of spikes, and a storm of Type III bursts, Type IIIb bursts, and a Type IV burst observed in the decameter band. During the observed time interval, the average flux of radio emission changed twice. Using spikes as a tool for diagnostics of plasma parameters, we followed variations of the coronal temperature and the coronal magnetic field in the observed time interval. Thus, in frames of the model described in this article the observed decameter spikes' durations of 0.3 -1 seconds correspond to the coronal plasma temperatures of ≈ 0.1 -0.6 × 10 6 K. At the same time the spikes' frequency bandwidths of 25 -80 kHz give us the magnetic-field value of about 2 G. B N.V. Shevchuk mykola.shevchuk@rian.kharkov.ua V.N. Melnik Melnik@rian.kharkov.ua S. Poedts Stefaan.Poedts@wis.kuleuven.be J. Magdalenic

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The properties of solar radio spikes with harmonics and the associated EUV brightenings

Feng

2019

Astrophys Space Sci

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Solar Decameter Spikes

Cited by 33 publications

References 16 publications

High resolution observations with Artemis-IV and the NRH

High resolution observations with Artemis-IV and the NRH

The Storm of Decameter Spikes During the Event of 14 June 2012

The properties of solar radio spikes with harmonics and the associated EUV brightenings

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