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With the elementary energy release events introduced in a previous paper (Liu & Fletcher 2009) we model the chromospheric evaporation in flaring loops. The thick-target hard X-ray (HXR) emission produced by electrons escaping from the…

Solar and Stellar Astrophysics · Physics 2014-11-20 Siming Liu , Feiran Han , Lyndsay Fletcher

Sequences of line-of-sight (LOS) magnetograms recorded by the Michelson-Doppler Imager are used to quantitatively characterize photospheric magnetic structure and evolution in three active regions that rotated across the Sun's disk during…

Solar and Stellar Astrophysics · Physics 2015-05-27 B. T. Welsch , S. Christe , J. M. McTiernan

We study photospheric and sub-photospheric properties of active and quiet regions observed during 11-17 February 2011 including the first X-class flare X2.2 of the solar cycle 24 which occurred in the active region NOAA 11158 on 15 February…

Solar and Stellar Astrophysics · Physics 2013-10-25 R. A. Maurya

Based on detailed analysis of radio and X-ray observations of a flare on 2002 April 11 augmented by realistic 3D modeling, we have identified a radio emission component produced directly at the flare acceleration region. This acceleration…

Solar and Stellar Astrophysics · Physics 2015-06-15 Gregory D. Fleishman , Eduard P. Kontar , Gelu M. Nita , Dale E. Gary

Waves are important for the heating of the solar corona and the acceleration of the solar wind. We have examined a long spectral time series of a northern coronal hole observed on the 20th October 1996, with the SUMER spectrometer onboard…

Solar and Stellar Astrophysics · Physics 2009-02-17 G. R. Gupta , E. O'Shea , D. Banerjee , M. Popescu , J. G. Doyle

We perform multiwavelength time-distance analysis of a fan loop system anchored in an isolated sunspot region AR 12553. The active region was observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. We measure…

Solar and Stellar Astrophysics · Physics 2020-07-01 Aishawnnya Sharma , Durgesh Tripathi , Robertus Erdelyi , G. R. Gupta , G. A. Ahmed

Most studies of quasi-periodic pulsations in solar flares have identified characteristic periods in the 5 - 300s range. Due to observational limitations there have been few attempts to probe the < 5s period regime and understand the…

Solar and Stellar Astrophysics · Physics 2024-06-12 Andrew R. Inglis , Laura A. Hayes

We report high sensitivity dual-frequency observations of radio oscillations from GRS 1915+105 following the decay of a major flare event in 2000 July. The oscillations are clearly observed at both frequencies, and the time-resolved…

Astrophysics · Physics 2009-11-07 R. P. Fender , D. Rayner , S. A. Trushkin , K. O'Brien , R. J. Sault , G. G. Pooley , R. P. Norris

A solar active region (AR) that produces at least one M- or X-class major flare tends to produce multiple flares during its passage across the solar disk. It will be interesting if we can estimate how flare-productive a given major flaring…

Solar and Stellar Astrophysics · Physics 2018-12-12 Eo-Jin Lee , Sung-Hong Park , Yong-Jae Moon

In the standard model, magnetic reconnection at a vertical current sheet above the flare arcade is key to explaining many aspects of solar eruptions. The supra-arcade region is where the vertical current sheet is supposedly located, and…

Solar and Stellar Astrophysics · Physics 2025-12-23 Hanya Pan , Astrid M. Veronig , Rui Liu

We study the coronal magnetic field structure inside active regions and its temporal evolution. We attempt to compare the magnetic configuration of an active region in a very quiet period with that for the same region during a flare.…

Astrophysics · Physics 2009-11-13 J. K. Thalmann , T. Wiegelmann , N. -E. Raouafi

We investigate the ability to constrain oscillatory features in the primordial power spectrum using current and future cosmic microwave background observations. In particular, we study the observability of an oscillation arising from…

Astrophysics · Physics 2011-05-12 Takemi Okamoto , Eugene A. Lim

The frequencies of the solar acoustic oscillations vary over the activity cycle. The variations in other activity proxies are found to be well correlated with the variations in the acoustic frequencies. However, each proxy has a slightly…

Solar and Stellar Astrophysics · Physics 2016-12-07 A. R. G. Santos , M. S. Cunha , P. P. Avelino , W. J. Chaplin , T. L. Campante

Lim et al. (2023) have recently proposed that the slope ($\delta$) of the power law distribution between the energy flux and oscillation frequency could determine whether high-frequency transverse oscillations give a dominant contribution…

Solar and Stellar Astrophysics · Physics 2024-08-28 Daye Lim , Tom Van Doorsselaere , David Berghmans , Elena Petrova

We study the properties of high degree p-mode oscillations in flaring and dormant ARs and compare them with those in corresponding quiet regions (QRs) to find the association of mode parameters with magnetic and flare related activities.…

Solar and Stellar Astrophysics · Physics 2015-06-17 R. A. Maurya , A. Ambastha , J. Chae

The origin of multiple peaks in lightcurves of various wavelengths remains illusive during flares. Here we discuss the flare of SOL2023-05-09T03:54M6.5 with six flux peaks as recorded by a tandem of new microwave and Hard X-ray instruments.…

Context. There remains much mystery about how or if wave-energy in the photosphere can be transferred sufficiently upwards through the solar atmosphere to contribute to coronal heating. In light of a plethora of theoretical and idealised…

Solar and Stellar Astrophysics · Physics 2026-01-14 George Cherry , Boris Gudiksen , Adam J. Finley , Quentin Noraz

Filament longitudinal oscillations have been observed on the solar disk in H$\alpha$. We intend to find an example of the longitudinal oscillations of a prominence, where the magnetic dip can be seen directly, and examine what is the…

Solar and Stellar Astrophysics · Physics 2015-06-04 Qingmin Zhang , Pengfei Chen , Chun Xia , Rony Keppens

GRS 1915+105 has been well studied since its discovery, and is well-known for its complex light curve variability. Using the full currently available Insight-HXMT dataset from July 2017 to June 2023, we make a comprehensive spectral-timing…

High Energy Astrophysical Phenomena · Physics 2025-10-14 Xiao Chen , Weiping Liu , Wei Wang

We report the discovery of milli-hertz (mHz) quasi-periodic oscillations (QPOs) and QPO-modulated pulsations during large X-ray flares from the high-mass X-ray binary pulsar LMC X-4 using data from the Rossi X-Ray Timing Explorer (RXTE).…

Astrophysics · Physics 2009-11-06 Dae-Sik Moon , Stephen. S. Eikenberry