Related papers: The solar X-ray continuum measured by RESIK

Extensive X-ray and extreme ultraviolet (EUV) photometric observations of the eclipsing RS CVn system AR Lac were obtained over the years 1997 to 2013 with the Chandra X-ray Observatory Extreme Ultraviolet Explorer. During primary eclipse,…

(Abridged) We present results of XMM-Newton observations of the RS CVn binary $\sigma^2$ Coronae Borealis. The RGS and EPIC MOS2 spectra were simultaneously fitted with collisional ionization equilibrium plasma models to determine coronal…

We have conducted a widefield, wideband, snapshot survey using the Australian SKA Pathfinder (ASKAP) referred to as the Rapid ASKAP Continuum Survey (RACS). RACS covers $\approx$ 90% of the sky, with multiple observing epochs in three…

On January 10 and 13, 2001, Venus was observed for the first time with an X-ray astronomy satellite. The observation, performed with the ACIS-I and LETG/ACIS-S instruments on Chandra, yielded data of high spatial, spectral, and temporal…

Recent SECCHI COR2 observations on board STEREO-A spacecraft have detected density structures at a distance of 2.5--15~R propagating with periodicity of about 90~minutes. The observations show that the density structures probably formed in…

We present the first clear detection of ionized Fe-K emission and absorption components in the nearby radio galaxy Centaurus A, revealed by the high-resolution XRISM/Resolve detector. In the 6.5-6.9 keV band, XRISM reveals multiple Fe XXV…

There are relatively few observations of UV emission during the impulsive phases of solar flares, so the nature of that emission is poorly known. Photons produced by solar flares can resonantly scatter off atoms and ions in the corona.…

The flare/spotted spectroscopic binary star CC Eri was observed with the Position Sensitive Proportional Counter (PSPC) on the X-ray satellite ROSAT on 1990 July 9-11 and 1992 January 26-27. During the observations, the source was variable…

We present Extreme Ultraviolet Explorer spectroscopy and photometry of the nearby F8 V star HD 35850 (HR 1817). The EUVE spectra reveal 28 emission lines from Fe IX and Fe XV to Fe XXIV. The Fe XXI 102, 129 A ratio yields an upper limit for…

Spectroscopic studies of the solar corona, using the high spatial and spectral resolution 25-cm coronagraph at the Norikura observatory for equatorial off-limb observations, indicated that the variation of radiance and line width with…

The presence of flare related acoustic emission (sunquakes) in some flares represents a severe challenge to our current understanding of flare energy transport processes. We present a comparison of new spectral observations from Hinode's…

Height series of H${\alpha}$ spectra in solar limb spicules obtained with the 53 cm coronagraph of the Abastumani Astrophysical Observatory are analyzed. Each height series covered 8 different heights beginning at 3800 km above the…

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…

Cosmic-ray proton and helium spectra have been measured with the balloon-borne Cosmic Ray Energetics And Mass experiment flown for 42 days in Antarctica in the 2004-2005 austral summer season. High-energy cosmic-ray data were collected at…

The solar disk is among the brightest gamma-ray sources in the sky. It is also among the most mysterious. No existing model fully explains the luminosity, spectrum, time variability, and morphology of its emission. We perform the first…

We analyse the aperiodic flaring features, also known as shots, observed in Cyg X-1 in the 0.1-80 keV energy band using a 6.39 ks simultaneous observation with AstroSat and NICER. We detect 49 simultaneous shots in the soft and hard X-ray…

We describe observations of a white-light flare (SOL2011-02-24T07:35:00, M3.5) close to the limb of the Sun, from which we obtain estimates of the heights of the optical continuum sources and those of the associated hard X-ray sources.For…

Context: Solar flares release a large fraction of their energy into non-thermal electrons, but it is not clear where and how. Bremsstrahlung X-rays are observed from the corona and chromosphere. Aims: We aim to characterize the acceleration…

By accumulating data from the Solid-state Slit Camera (SSC) on board the MAXI mission for 2 years from 2009 to 2011, diffuse X-ray background maps were obtained in energies of 0.7--1.0, 1.0--2.0, and 2.0--4.0 keV. They are the first ones…

We present the first observations of quiescent active regions (ARs) using NuSTAR, a focusing hard X-ray telescope capable of studying faint solar emission from high temperature and non-thermal sources. We analyze the first directly imaged…