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Extreme ultraviolet (EUV) waves, spectacular horizontally propagating disturbances in the low solar corona, always trigger horizontal secondary waves (SWs) when they encounter ambient coronal structure. We present a first example of upward…

Solar and Stellar Astrophysics · Physics 2018-05-02 Ruisheng Zheng , Yao Chen , Shiwei Feng , Bing Wang , Hongqiang Song

An admittedly pedantic but hopefully useful and informative analysis is presented of the EUVE 70--180 Angstrom spectra of nine polars. These spectra are fit with three different models---a blackbody, a pure-H stellar atmosphere, and a solar…

Astrophysics · Physics 2007-05-23 Christopher W. Mauche

High-energy emission spectra from the outer atmospheres of late-type stars represent an important feature of the stellar activity in several contexts, such as the photoevaporation and photochemistry of planetary atmospheres or the modeling…

Solar and Stellar Astrophysics · Physics 2025-11-17 Antonio Maggio , Ignazio Pillitteri , Jorge Sanz-Forcada , Giuseppina Micela

The Geostationary Operational Environmental Satellite R (GOES-R) series of four satellites are the next generation NOAA GOES satellites. Once on orbit and commissioned, they are renamed GOES 16-19, making critical terrestrial and space…

Understanding the initiation of solar flares and coronal mass ejections (CMEs) is essential for improving forecasts of extreme space weather. Soft X-ray (SXR) and Extreme Ultraviolet (EUV) observations provide critical diagnostics of the…

Context. Solar spectral irradiance (SSI) variability is one of the key inputs to models of the Earth's climate. Understanding solar irradiance fluctuations also helps to place the Sun among other stars in terms of their brightness…

Solar and Stellar Astrophysics · Physics 2019-11-20 R. V. Tagirov , A. I. Shapiro , N. A. Krivova , Y. C. Unruh , K. L. Yeo , S. K. Solanki

On 12 March 1996 we obtained observations of the quiet Sun with the SUMER instrument. The observa- tions were sequences of 15-20 second exposures of ultraviolet emission line profiles and of the neighboring continua. These data contain…

Astrophysics · Physics 2009-10-30 Mats Carlsson , Philip G. Judge , Klaus Wilhelm

Daily differential emission measure (DEM) distributions of the solar corona are derived from spectra obtained by the Extreme-ultraviolet Variability Experiment (EVE) over a 4-year period starting in 2010 near solar minimum and continuing…

Solar and Stellar Astrophysics · Physics 2020-09-16 Samuel J. Schonfeld , Stephen M. White , Rachel A. Hock-Mysliwiec , R. T. James McAteer

Using detrended fluctuation analysis (DFA) and rescaled range (R/S) analysis, we investigate the scaling properties of EUV intensity fluctuations of low-latitude coronal holes (CHs) and neighboring quiet-Sun (QS) regions in signals obtained…

Solar and Stellar Astrophysics · Physics 2020-01-08 Ana Cristina Cadavid , Mari Paz Miralles , Kristine Romich

We aim to reproduce the structure of the corona above a solar active region as seen in the extreme ultraviolet (EUV) using a three-dimensional magnetohydrodynamic (3D MHD) model. The 3D MHD data-driven model solves the induction equation…

Solar and Stellar Astrophysics · Physics 2019-04-30 Jörn Warnecke , Hardi Peter

Total and spectral solar irradiance are key parameters in the assessment of solar influence on changes in the Earth's climate. We present a reconstruction of daily solar irradiance obtained using the SATIRE-S model spanning 1974 to 2013…

Solar and Stellar Astrophysics · Physics 2015-07-07 K. L. Yeo , N. A. Krivova , S. K. Solanki , K. H. Glassmeier

The present solar cycle is particular in many aspects: it had a delayed rising phase, it is the weakest of the last 100 years, and it presents two peaks separated by more than one year. To understand the impact of these characteristics on…

Solar and Stellar Astrophysics · Physics 2017-11-08 A. J. Oliveira e Silva , C. L. Selhorst , P. J. A. Simões , C. G. Giménes de Castro

Aims: This paper aims to demonstrate the importance of short-exposure extreme ultraviolet (EUV) observations of solar flares in the study of particle acceleration, heating and energy partition in flares. This work highlights the…

The determination of the cutoff frequency in real solar observations under different local physical conditions is an important and insufficiently explored aspect of waves in solar physics. This work utilizes the near ultraviolet (NUV)…

Solar and Stellar Astrophysics · Physics 2026-05-14 Pradeep Kayshap , Gayathri Hegde , Z. E. Musielak , Kris Murawski , Tobıas Felipe

The Sun Watcher with Active Pixels and Image Processing (SWAP) EUV solar telescope on board the Project for On-Board Autonomy 2 (PROBA2) spacecraft has been regularly observing the solar corona in a bandpass near 17.4 nm since February…

Solar and Stellar Astrophysics · Physics 2015-06-17 Daniel B. Seaton , Anik De Groof , Paul Shearer , David Berghmans , Bogdan Nicula

The evaporation and the chemistry of the atmospheres of warm and hot planets are strongly determined by the high-energy irradiation they receive from their parent stars. This is more crucial among young extra-solar systems, due to the high…

Solar and Stellar Astrophysics · Physics 2024-10-23 A. Maggio , I. Pillitteri , C. Argiroffi , D. Locci , S. Benatti , G. Micela

We present a model for the intensity of optically thin EUV emission for a plasma atmosphere. We apply our model to the solar corona as observed using the six optically thin EUV channels of the SDO/AIA instrument. The emissivity of the…

Solar and Stellar Astrophysics · Physics 2020-03-31 D. J. Pascoe , A. Smyrli , T. Van Doorsselaere

Extreme UltraViolet (EUV) images of the optically-thin solar corona in multiple spectral channels give information on the emission as a function of temperature through differential emission measure (DEM) inversions. The aim of this paper is…

Solar and Stellar Astrophysics · Physics 2019-10-09 Huw Morgan , James Pickering

Extreme precision radial-velocity spectrometers enable extreme precision stellar spectroscopy. Searches for low-mass exoplanets around solar-type stars are limited by the physical variability in stellar spectra, such as the short-term…

Solar and Stellar Astrophysics · Physics 2023-11-01 Dainis Dravins , Hans-Günter Ludwig

For the first time, we present and discuss EUV radiances of the solar transition region (TR) and corona obtained during a solar cycle. The measurements were obtained with the SOHO/coronal diagnostic spectrometer (CDS) during the period from…

Solar and Stellar Astrophysics · Physics 2017-03-30 V. Andretta , G. Del Zanna