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Time-resolved diagnostics were applied to investigate free-electron properties in nanosecond laser-produced discharges sustained at atmospheric pressure in Ar and in Ar with 3% H2O. The discharges were generated using 23 ns, 1064 nm laser…

Plasma Physics · Physics 2026-01-27 Ji Yung Ahn , Jianan Wang , Tasnim Akbar Faruquee , Marien Simeni Simeni

Quasi-periodic oscillations in solar flaring emission have been observed over the past few decades. To date, the underpinning processes resulting in the quasi-periodic oscillations remain unknown. In this paper, we report a unique event…

Solar and Stellar Astrophysics · Physics 2024-07-08 Yining Zhang , Ting Li , Jing Ye

Super-hot looptop sources, detected in some large solar flares, are compact sources of HXR emission with spectra matching thermal electron populations exceeding 30 megakelvins. High observed emission measure, as well as inference of…

Solar and Stellar Astrophysics · Physics 2015-05-28 D. W. Longcope , S. E. Guidoni

We present the analyses of intense X-ray flares detected on the active fast rotator AB Dor using observations from the XMM-Newton. A total of 21 flares are detected, and 13 flares are analysed in detail. The total X-ray energy of these…

Solar and Stellar Astrophysics · Physics 2023-10-23 Shweta Didel , Jeewan C. Pandey , A. K. Srivastava , Gurpreet Singh

A popular scenario for electron acceleration in solar flares is transit-time damping of low-frequency MHD waves excited by reconnection and its outflows. The scenario requires several processes in sequence to yield energetic electrons of…

Astrophysics · Physics 2015-06-24 Arnold O. Benz , Pascal Saint-Hilaire

Solar flare termination shocks have been suggested as one of the viable mechanisms for accelerating electrons and ions to high energies. Observational evidence of such shocks, however, remains rare. Using radio dynamic spectroscopic imaging…

Solar and Stellar Astrophysics · Physics 2021-04-21 Yingjie Luo , Bin Chen , Sijie Yu , T. S. Bastian , Säm Krucker

Coronal loops in active regions are the subjects of intensive investigation, but the important diffuse 'unresolved' emission in which they are embedded has received relatively little attention. Here we measure the densities and emission…

Solar and Stellar Astrophysics · Physics 2019-03-06 David H. Brooks

White-light flares are explosive phenomena accompanied by brightening of continuum from near-ultraviolet to optical, which occur on the Sun and stars. In order to investigate the mechanism of white-light flares, we carried out simultaneous…

We investigate the relationship between the continuum enhancement and the hard X-ray (HXR) emission of a white-light flare on 2002 September 29. By reconstructing the RHESSI HXR images in the impulsive phase, we find two bright conjugate…

Astrophysics · Physics 2014-10-13 Q. R. Chen , M. D. Ding

We report high-resolution observations at mid-infrared wavelengths of a minor solar flare, SOL2014-09-24T17T17:50 (C7.0), using Quantum Well Infrared Photodetector (QWIP) cameras at an auxiliary of the McMath-Pierce telescope. The flare…

Solar and Stellar Astrophysics · Physics 2016-03-23 M Penn , S Krucker , H Hudson , M Jhabvala , D Jennings , A Lunsford , P Kaufmann

Recent observations from {\em RHESSI} have revealed that the number of non-thermal electrons in the coronal part of a flaring loop can exceed the number of electrons required to explain the hard X-ray-emitting footpoints of the same flaring…

Solar and Stellar Astrophysics · Physics 2015-06-18 E. P. Kontar , N. H. Bian , A. G. Emslie , N. Vilmer

Solar flares result in an increase of the solar irradiance at all wavelengths. While the distribution of the flare fluence observed in coronal emission has been widely studied and found to scale as f(E) ~ E^{-\alpha}, with \alpha slightly…

Solar and Stellar Astrophysics · Physics 2015-10-08 M. Kretzschmar

As part of the first far-IR line survey towards Orion KL, we present the detection of seven new rotationally excited OH Lambda-doublets (at 48, 65, 71, 79, 98 and 115 um). Observations were performed with the Long Wavelength Spectrometer…

We present echelle spectrophotometry of the Galactic H II region S 311. The data have been taken with the Very Large Telescope UVES echelle spectrograph in the 3100 to 10400 angstroms range. We have measured the intensities of 263 emission…

Astrophysics · Physics 2009-11-13 J. Garcia-Rojas , C. Esteban , A. Peimbert , M. Peimbert , M. Rodriguez , M. T. Ruiz

We present a detailed analysis of a high resolution spectrum of the damped Ly$\alpha$ system at $z_{\rm abs}$~=~2.8112toward PKS~0528-250. The absorption redshift is slightly larger than the emission redshift of the quasar. We estimate the…

Astrophysics · Physics 2007-05-23 R. Srianand , P. Petitjean

The high densities, long lifetimes, and narrow emission measure distributions observed in coronal loops with apex temperatures near 1 MK are difficult to reconcile with physical models of the solar atmosphere. It has been proposed that the…

Solar and Stellar Astrophysics · Physics 2010-04-08 Harry P. Warren , David M. Kim , Amanda M. DeGiorgi , Ignacio Ugarte-Urra

We analyze a pair of Suzaku shadowing observations in order to determine the X-ray spectrum of the Galaxy's gaseous halo. We simultaneously fit the spectra with models having halo, local, and extragalactic components. The intrinsic…

Astrophysics of Galaxies · Physics 2009-07-24 Shijun Lei , Robin L. Shelton , David B. Henley

We consider the statistics of density number of filaments for the propagation of a laser beam subjected to multiple filamentation in a closed area with reflecting boundaries. Dissipation arrests the catastrophic collapse of filaments,…

Optics · Physics 2012-08-21 A. D. Bulygin

In this work, I have presented a multi-frequency variability and correlation study of the blazar Ton 599, which was observed first time in flaring state at the end of 2017. Data from \textit{Fermi}-LAT, Swift-XRT/UVOT, Steward Observatory,…

High Energy Astrophysical Phenomena · Physics 2019-01-30 Raj Prince

The energy released during solar flares is believed to be stored in non-potential magnetic fields associated with electric currents flowing in the corona. While no measurements of coronal electric currents are presently available, maps of…

Solar and Stellar Astrophysics · Physics 2015-08-19 Sophie Musset , Nicole Vilmer , Véronique Bommier