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* News 04/04/20 * The archive is using a new backend database. This has thrown up a few SQL errors in the last few days. If you have any issues please email adavey@nso.edu with either the number of eprint you are trying to edit or a link to your preprint.

QUASI-PERIODIC PULSATIONS IN SOLAR AND STELLAR FLARES. REVIEW  

Elena Kupriyanova   Submitted: 2020-04-07 10:01

This paper provides an overview of the state-of-the-art studies of oscillatory processes in solar and stellar flares, based on modern observational data from ground-based and space-borne instruments with high temporal, spatial, and spectral resolution in different bands of the electromagnetic spectrum. We examine the mechanisms that generate flare emission and its quasi-periodic modulation. We discuss similarities and differences between solar and stellar flares, and address associated problems of superflares on the Sun and space weather. Quasi-periodic pulsations (QPPs) of flare emission are shown to be an effective tool for diagnosing both the flare processes themselves and the parameters of flaring plasmas and accelerated particles. We consider types of QPPs, their statistical properties, and methods of analysis, taking into account the non-stationarity of the QPPs parameters. We review the proposed mechanisms of QPPs and summarize open questions.

Authors: E.G. Kupriyanova, D.Yu. Kolotkov, V.M. Nakariakov, A.S. Kaufman
Projects: None

Publication Status: published
Last Modified: 2020-04-10 09:42
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Relationship of type III radio bursts with quasi-periodic pulsations in a solar flare  

Elena Kupriyanova   Submitted: 2016-08-04 06:30

We studied a solar flare with pronounced quasi-periodic pulsations detected in the microwave, X-ray, and radio bands. We used the methods of correlation, Fourier, and wavelet analyses to examine the temporal fine structures and relationships between the time profiles in each wave band. We found that the time profiles of the microwaves, hard X-rays and type III radio bursts vary quasi-periodically with the common period of 40-50 s. The average amplitude of the variations is high, above 30% of the background flux level and reaching 80% after the flare maximum. We did not find the periodicity in either the thermal X-ray flux component or source size dynamics. Our findings indicate that the detected periodicity is likely to be associated with periodic dynamics in the injection of non-thermal electrons, that can be produced by periodic modulation of magnetic reconnection.

Authors: E. G. Kupriyanova, L. K. Kashapova, H. A. S. Reid, I. N. Myagkova
Projects: CORONAS-F,Nobeyama Radioheliograph,RHESSI

Publication Status: accepted to Solar Physics, in press
Last Modified: 2016-08-05 15:28
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Spatially Resolved Microwave Observations of Multiple Periodicities in a Flaring Loop  

Elena Kupriyanova   Submitted: 2013-05-06 03:22

Quasi-periodic pulsations (QPPs) with at least three simultaneously existing spectral components with periods P≥30 s, P≈20 s, and about P≈10 s were detected during the decay phase of a solar flare on 3 July 2002, observed with the Nobeyama Radioheliograph (NoRH). A detailed study of the spatial structure of the Fourier amplitudes of QPPs along a flaring loop has revealed different spatial distributions of the three components. It is shown that the source of the QPPs with period P≥30 s has its maximum amplitude in the inner region of the loop, between the footpoints. QPPs with period P≈20 s are localized at the periphery of the loop, mainly in the outer parts of the footpoints. The spatial distribution of oscillations with period about P≈10 s contains three regions of high QPP amplitudes: two near the footpoints and one in the middle of the flaring region. It is shown that the observed properties of the spectral components are most accurately described by the fundamental, second, and third harmonics of the kink mode standing waves. This is the first identification of the kink mode in flare loops which is based on strict limitations derived from data on the spatial structure of a pulsating flare region.

Authors: Kupriyanova, E. G.; Melnikov, V. F.; Shibasaki, K.
Projects: Nobeyama Radioheliograph

Publication Status: published
Last Modified: 2013-05-06 11:08
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Abstracts by Author
QUASI-PERIODIC PULSATIONS IN SOLAR AND STELLAR FLARES. REVIEW
Relationship of type III radio bursts with quasi-periodic pulsations in a solar flare
Spatially Resolved Microwave Observations of Multiple Periodicities in a Flaring Loop

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