Related papers: Highly ionized Fe X-ray lines at energies 7.7-8.6 …
Gamma-ray emitting solar flares observed with Yohkoh were analyzed from a statistical viewpoint. The four-band hard X-ray (15--95 keV) photometric data, taken with the Hard X-ray Telescope onboard Yohkoh, were utilized in combination with…
SDO/EVE provides rich information of the thermodynamic processes of solar activities, particularly of solar flares. Here, we develop a method to construct thermodynamic spectrum (TDS) charts based on the EVE spectral lines. This tool could…
Numerical models of solar flares typically focus on the behaviour of directly-heated flare models, adopting magnetic field- aligned, plane-parallel methodologies. With high spatial- and spectral-resolution ground-based optical observations…
Solar flare activity in cycle 24 is studied. Satellite observations of x-ray fluxes from GOES-15 and UV emission lines from the SDO/EVE experiment are used. The most powerful flares of cycle 24 in classes X9.3 and X8.2 in September 2017 are…
As the Lyman-alpha (Lya) line of neutral hydrogen is the brightest emission line in the solar spectrum, detecting increases in irradiance due to solar flares at this wavelength can be challenging due to the very high background. Previous…
Fe K$\alpha$ line emission from Galactic center molecular clouds can be produced either via fluorescence after illumination by an X-ray source or by cosmic ray ionization. Unparalleled high-resolution X-ray spectroscopy obtained by…
Studying the statistical properties of solar ultraviolet emission lines could provide information about the nature of small scale coronal heating. We expand on previous work to investigate these properties. We study whether the predicted…
Superflares on the solar type stars observed by \textit{Kepler} demonstrate the contrast in the optical continuum of the order 0.1--1 per cent. The mechanism of formation of this radiation is not firmly established. We consider a model…
The Fe K$\alpha$ fluorescence line at 6.4 keV is a powerful probe of cold matter surrounding X-ray sources and has been widely used in various astrophysical contexts. The X-ray microcalorimeter spectrometer onboard XRISM can measure line…
The properties of the Galactic Ridge X-ray Emission (GRXE) observed in the 2-10 keV band place fundamental constraints on various types of X-ray sources in the Milky Way. Although the primarily discrete origin of the emission is now well…
Solar flare X-ray spectra are typically dominated by thermal bremsstrahlung emission in the soft X-ray ($\lesssim$10 keV) energy range; for hard X-ray energies ($\gtrsim$30 keV), emission is typically non-thermal from beams of electrons.…
Future ground-based telescopes will expand our capabilities for simultaneous multi-line polarimetric observations in a wide range of wavelengths, from the near-ultraviolet to the near-infrared. This creates a strong demand to compare…
We present an analysis of seven flares detected from five RS CVn-type binaries (UZ Lib, \sigma Gem, \lambda And, V711 Tau and EI Eri) observed with XMM-Newton observatory. The quiescent state X-ray luminosities in the energy band of…
With the aim of studying AR fan loops using Hinode/EIS and SDO/AIA, we investigate a number of inconsistencies in modeling the absolute intensities of Fe VIII and Si VII lines, and address why their images look very similar despite the fact…
We investigate the possibility of diagnosing the degree of departure from the Maxwellian distribution using single-ion spectra originating in astrophysical plasmas in collisional ionization equilibrium. New atomic data for excitation of Fe…
We analyze EUV spectra of the full solar disk from the Cosmic Hot Interstellar Plasma Spectrometer (CHIPS) spanning a period of two years. The observations were obtained via a fortuitous off-axis light path in the 140 -- 270 Angstrom…
With the purpose of assessing classic spectroscopic methods on high-resolution and high signal-to-noise ratio spectra in the near-infrared wavelength region, we selected a sample of 65 F-, G-, and K-type stars observed with CARMENES, the…
We report on the structure and evolution of a current sheet that formed in the wake of an eruptive X8.3 flare observed at the west limb of the Sun on September 10, 2017. Using observations from the EUV Imaging Spectrometer (EIS) on Hinode…
We present the results of a Suzaku spectroscopic study of the soft extended X-ray emission in the HII region M17. The spectrum of the extended emission was obtained with a high signal-to-noise ratio in a spatially-resolved manner using the…
Spectroscopic analysis of large flares (>X1) in the hard X-ray (HXR) range offers unique insights into the hottest (> 30 MK) flare plasma, the so-called superhot thermal component. To manage the high count rates in large flares, an…