On the Observational Properties of the Decameter Striae

Shevchuk, N. V.; Melnik, V.; Poedts, Stefaan; Dorovskyy, V. V.; Magdalenić, Jasmina; Konovalenko, Alexander

doi:10.23919/ursi-at-rasc.2018.8471315

Cited by 3 publications

(4 citation statements)

References 16 publications

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“…The average value of the Type IIIb bursts polarization varied from 40% ± 10% to 60% ± 10% depending on the day of observation and its sign coincided with the polarization sign of the associated Type III bursts. This result along with the results presented in (Shevchuk et al, 2018) might be additional evidence that spikes and striae, which form Type IIIb burst, are apparently the same type of the solar radio bursts.…”

Section: Analysis Of the Observational Datasupporting

confidence: 79%

Polarization properties of the decameter spikes

Shevchuk,

Melnik,

Brazhenko

et al. 2024

Front. Astron. Space Sci.

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An analysis of the observational polarization properties of the decameter spikes is presented in the paper. It is shown that decameter spikes possess high degree of circular polarization with average value of about 60%. In the frames of “leading spot” theory we associated the spikes activity with a certain active region on the solar disk and determined the mode of the emission. Supposing plasma emission mechanism we link and determine coronal plasma and fast electron beam parameters.

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Section: Analysis Of the Observational Datasupporting

confidence: 79%

Polarization properties of the decameter spikes

Shevchuk,

Melnik,

Brazhenko

et al. 2024

Front. Astron. Space Sci.

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“…The sense and degree of polarization of decameter spikes agree well with those obtained for the decameter Type IIIb bursts. This fact can be additional evidence that spikes and striae, which form Type IIIb bursts, are the same type of the solar radio bursts [Shevchuk M. V., et al, 2018].…”

Section: Resultsmentioning

confidence: 67%

Book of Proceedings Tenth Workshop Primorsko, Bulgaria 2019

Nikitenko¹,

Lebed²,

Fedorenko³

et al. 2019

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The Catalogues of the solar proton events [Logachev, ed., 1982-2016] provide the homogeneous data series of events with maximum intensity of > 10 MeV solar protons J ≥ 1 cm-2 s-1 sr-1 beginning from 1970 up to now. The event rates behavior is rather smooth: the total number of such events, relative to accumulated sunspot number, is almost constant in the solar cycles 21-23 and even slightly growing in the solar cycle 24. Contrary, the total number of the most powerful (GLE) events per cycle was constant within statistical errors in the cycles 21-23, and it fell abruptly in cycle 24. Considering the conventional sources of GLEs we found that production of GLEs by X-class bursts was 3 times less in cycle 24 than in cycle 23, while production of GLEs by the >1000 km/s halo-type CMEs was 5 times lower.

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“…However, a considerably wider frequency band of available observational data allowed to determine the dependences of striae durations and bandwidths on frequency. Thus it was found that the straie durations decreased with increasing frequency as On basis of the results obtained and assuming the plasma emission mechanism the authors supposed that the durations and the bandwidths of stria bursts were apparently determined by the temperature and the magnetic fi eld in the place of generation, just as it took place for the decameter spikes [20]. The mean temperature obtained under such assumptions equaled to 0.28 K, and the magnetic fi eld was approximately 1.8 G at the distance of 1.9 .…”

Section: Type Iiib-iiid Burstsmentioning

confidence: 94%

“…It was shown that the Type IIIb bursts were predominantly observed simultaneously with the Type III bursts and consisted of a number of separate striae [19,20]. The total amount of individual striae in one Type IIIb burst in the frequency range of 8 32  MHz could exceed 95.…”

Section: Type Iiib-iiid Burstsmentioning

confidence: 99%

Exploration of the Solar Decameter Radio Emission With the Utr-2 Radio Telescope

Melnik

Konovalenko

Dorovskyy

et al. 2021

Radio phys. radio astron.

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Purpose: The overview of the scientifi c papers devoted to the study of the solar decameter radio emission with the world’s largest UTR-2 radio telescope (Ukraine) published for the last 50 years. Design/methodology/approach: The study and analysis of the scientifi c papers on both sporadic and quiet (thermal) radiation of the Sun recorded with the UTR-2 radio telescope at the decameter wavelength range. Findings: The most signifi cant observational and theoretical results of the solar radio emission studies obtained at the Institute of Radio Astronomy of the National Academy of Sciences of Ukraine for the last 50 years are given. Conclusions: For the fi rst time, at frequencies below 30 MHz, the Type II bursts, Type IV bursts, S-bursts, drift pairs and spikes have been recorded. The dependences of these bursts parameters on frequency within the frequency band of 9 to 30 MHz were obtained. The models of their generation and propagation were suggested. Moreover, for the fi rst time the fi ne time-frequency structures of the Type III bursts, Type II bursts, Type IV bursts, U- and J-bursts, S-bursts, and drift pairs have been observed due to the high sensitivity and high time-frequency resolutions of the UTR-2 radio telescope. The super-fi ne structure of Type II bursts with a “herringbone” structure was identifi ed, which has never been observed before. New types of bursts were discovered: “caterpillar” bursts, “dog-leg” bursts, Type III bursts with decay, Type III bursts with changing drift rate sign, Type III-like bursts, Jb- and Ub-bursts, etc. An interpretation of the unusually high drift rates and drift rates with alternating signs of the Type III-like bursts was suggested. Based on the dependence of spike durations on frequency, the coronal plasma temperature profi le at the heliocentric heights of 1.5–3RS was determined. Usage of the heliographic and interferometric methods gave the possibility to start studies of the spatial characteristics – sizes and locations of the bursts emission sources. Thus, it was shown that at the decameter band, the Type III burst durations were defi ned by the emission source linear sizes, whereas the spike durations were governed by the collision times in the source plasma. It was experimentally proved that the effective brightness temperatures of the sources of solar sporadic radio emission at the decameter band may reach values of 1014–1015 K. In addition, it was found that the radii of the quiet Sun at frequencies 20 and 25 MHz are close to the distances from the Sun at which the local plasma frequency is equal to the corresponding observed frequency of radio emission in the Baumbach–Allen model. Key words: UTR-2; Sun; decameter radio emission; radio bursts; corona

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On the Observational Properties of the Decameter Striae

Cited by 3 publications

References 16 publications

Polarization properties of the decameter spikes

Polarization properties of the decameter spikes

Book of Proceedings Tenth Workshop Primorsko, Bulgaria 2019

Exploration of the Solar Decameter Radio Emission With the Utr-2 Radio Telescope

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