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In addition to well-known mechanisms of excitation of solar and stellar oscillations by turbulent convection and instabilities, the oscillations can be excited by an impulsive localized force caused by the energy release in solar and…

Solar and Stellar Astrophysics · Physics 2015-06-18 Alexander G. Kosovichev

A common feature of electromagnetic emission from solar flares is the presence of intensity pulsations that vary as a function of time. Known as quasi-periodic pulsations (QPPs), these variations in flux appear to include periodic…

Solar and Stellar Astrophysics · Physics 2021-04-14 Brendan P. Clarke , Laura A. Hayes , Peter T. Gallagher , Shane A. Maloney , Eoin P. Carley

Quasi-periodic pulsations (QPPs) appear to be a common feature observed in the light curves of both solar and stellar flares. However, their quasi-periodic nature, along with the fact that they can be small in amplitude and short-lived,…

We investigate quasi-periodic pulsations (QPPs) of high-energy nonthermal emissions from an X9.3 flare (SOL2017-Sep-06T11:53), the most powerful flare since the beginning of solar cycle 24. The QPPs are identified as a series of regular and…

Solar and Stellar Astrophysics · Physics 2020-01-15 D. Li , D. Y. Kolotkov , V. M. Nakariakov , L. Lu , Z. J. Ning

Context. Quasi-periodic pulsations (QPPs) typically display periodic and regular peaks in the light curves during the flare emissions. Sometimes, QPPs show multiple periods at the same wavelength. However, changing periods in various…

Solar and Stellar Astrophysics · Physics 2016-12-28 Dong Li , Qingmin Zhang , Yu Huang , Zongjun Ning , Yingna Su

Twisted coronal loops in the solar atmosphere may become kink-unstable when their magnetic field lines are sufficiently twisted. This instability can trigger magnetic reconnection, leading to the emission of electromagnetic radiation, which…

Solar and Stellar Astrophysics · Physics 2025-10-07 James Stewart , Philippa K. Browning , Mykola Gordovskyy

Low-frequency longitudinal oscillations of a flaring coronal loop are studied numerically. In the recent work of Nakariakov et al., Astron. and Astrophys., 414, L25-L28 (2004) it has been shown that the time dependences of density and…

Astrophysics · Physics 2009-11-10 D. Tsiklauri , V. M. Nakariakov , T. D. Arber , M. J. Aschwanden

Context. Extreme-ultraviolet (EUV) observations have revealed small-scale transient brightenings that may share common physical mechanisms with larger-scale solar flares. A notable feature of solar and stellar flares is the presence of…

Solar and Stellar Astrophysics · Physics 2025-05-28 Daye Lim , Tom Van Doorsselaere , David Berghmans , Laura A. Hayes , Cis Verbeeck , Nancy Narang , Marie Dominique , Andrew R. Inglis

Small amplitude quasi-periodic pulsations (QPPs) detected in soft X-ray emission are commonplace in many flares. To date, the underpinning processes resulting in the QPPs are unknown. In this paper, we attempt to constrain the prevalence of…

Solar and Stellar Astrophysics · Physics 2020-06-03 Laura A. Hayes , Andrew R. Inglis , Steven Christe , Brian Dennis , Peter T. Gallagher

Quasi-periodic pulsations (QPPs) are frequently detected in solar and stellar flares, but the underlying physical mechanisms are still to be ascertained. Here, we show microwave QPPs during a solar flare originating from quasi-periodic…

Solar and Stellar Astrophysics · Physics 2022-12-19 Yuankun Kou , Xin Cheng , Yulei Wang , Sijie Yu , Bin Chen , Eduard P. Kontar , Mingde Ding

Quasi-periodic pulsations (QPPs) are frequently observed in solar and stellar flare emission, with recent studies suggesting that an increasing instantaneous period is a common characteristic of QPPs. Determining the prevalence of…

Solar and Stellar Astrophysics · Physics 2023-06-01 Tishtrya Mehta , Anne-Marie Broomhall , Laura Hayes

Quasi-periodic pulsations (QPP) are often detected in solar and stellar flare lightcurves. These events may contain valuable information about the underlying fundamental plasma dynamics as they are not described by the standard flare model.…

Solar and Stellar Astrophysics · Physics 2024-08-12 Sergey A. Belov , Dmitrii Y. Kolotkov , Valery M. Nakariakov , Anne-Marie Broomhal

We report the detection of multiple quasi-periodic pulsations (QPPs) observed during the flaring activity of KIC 8414845, a young, active solar-type star observed by the Kepler mission launched by NASA. We analyzed the QQP signal using a…

Solar and Stellar Astrophysics · Physics 2020-04-29 S. Mancuso , D. Barghini , D. Telloni

Quasi-periodic pulsations (QPPs) with various periods that originate in the underlying magnetohydrodynamic processes of the flaring structures are detected repeatedly in the solar flare emissions. We apply a 2D cellular automaton (CA)…

Solar and Stellar Astrophysics · Physics 2022-09-14 Nastaran Farhang , Farhad Shahbazi , Hossein Safari

We investigate the properties of a set of solar flares originating from a single active region (AR) that exhibit QPPs, and look for signs of the QPP periods relating to AR properties. The AR studied, best known as NOAA 12192, was unusually…

Solar and Stellar Astrophysics · Physics 2017-12-13 C. E. Pugh , V. M. Nakariakov , A. -M. Broomhall , A. V. Bogomolov , I. N. Myagkova

We investigate the solar flare of 20 October 2002. The flare was accompanied by quasi-periodic pulsations (QPP) of both thermal and nonthermal hard X-ray emissions (HXR) observed by RHESSI in the 3-50 keV energy range. Analysis of the HXR…

Solar and Stellar Astrophysics · Physics 2015-05-14 I. V. Zimovets , A. B. Struminsky

An peculiar microwave quasi-periodic pulsation (QPP) accompanying with a hard X-ray (HXR) QPP of about 20 s duration occurred just before the maximum of an X6.9 solar flare on 2011 August 9. The most interesting is that the microwave QPP is…

Solar and Stellar Astrophysics · Physics 2015-06-04 Baolin Tan , Chengming Tan

Quasi-periodic pulsations (QPP) are often observed in X-ray emission from solar flares. To date, it is unclear what their physical origins are. Here, we present a multi-instrument investigation of the nature of QPP during the impulsive and…

Solar and Stellar Astrophysics · Physics 2016-08-24 Laura A. Hayes , Peter T. Gallagher , Brian R. Dennis , Jack Ireland , Andrew R. Inglis , Daniel F. Ryan

Flare-associated quasiperiodic pulsations (QPPs) in radio and X-ray wavelengths, particularly those related to nonthermal electrons, contain important information about the energy release and transport processes during flares. However, the…

Solar and Stellar Astrophysics · Physics 2022-12-02 Yingjie Luo , Bin Chen , Sijie Yu , Marina Battaglia , Rohit Sharma

The robust detection of quasi-periodic pulsations (QPPs) in solar and stellar flares has been the topic of recent debate. In light of this, we have adapted a method described by Vaughan (2005) to aid with the search for QPPs in flare time…

Solar and Stellar Astrophysics · Physics 2017-06-07 C. E. Pugh , A. -M. Broomhall , V. M. Nakariakov