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Nanoflares have been proposed as the main source of heating of the solar corona. However, detecting them directly has so far proved elusive, and extrapolating to them from the properties of larger brightenings gives unreliable estimates of…

Astrophysics · Physics 2009-11-11 Anuschka Pauluhn , Sami K. Solanki

Continuum emission from a solar flare observed with the Extreme ultraviolet Imaging Spectrometer (EIS) on board the Hinode satellite is used to obtain the radiometric calibration of the instrument. The flare had a GOES class of M8, and…

Solar and Stellar Astrophysics · Physics 2026-05-07 Peter R. Young , Biswajit Mondal

We present a study of the frequency of transient brightenings in the core of solar active regions as observed in the Fe XVIII line component of AIA/SDO 94 A filter images. The Fe XVIII emission is isolated using an empirical correction to…

Solar and Stellar Astrophysics · Physics 2015-06-18 Ignacio Ugarte-Urra , Harry P. Warren

We examine the temperature structure of static coronal active region loops in regimes where thermal conductive transport is driven by Coulomb collisions, by turbulent scattering, or by a combination of the two. (In the last case collisional…

Solar and Stellar Astrophysics · Physics 2022-11-09 A. Gordon Emslie , Stephen J. Bradshaw

Deriving a well-constrained differential emission measure (DEM) distribution for solar flares has historically been difficult, primarily because no single instrument is sensitive to the full range of coronal temperatures observed in flares,…

Solar and Stellar Astrophysics · Physics 2014-06-25 Amir Caspi , James M. McTiernan , Harry P. Warren

The extreme ultraviolet portion of the solar spectrum contains a wealth of diagnostic tools for probing the lower solar atmosphere in response to an injection of energy, particularly during the impulsive phase of solar flares. These include…

Solar and Stellar Astrophysics · Physics 2015-09-16 Ryan O. Milligan

We present a study of spectral line width measurements from the Extreme Ultraviolet Imaging Spectrometer (EIS) on {\it Hinode}. We used spectral line profiles of Fe {\sc xvi} 262.984 {\AA}, Fe {\sc xiv} 264.787 {\AA}, Fe {\sc xiv} 270.519…

Solar and Stellar Astrophysics · Physics 2024-04-29 M. Asgari-Targhi , D. H. Brooks , M. Hahn , S. Imada , E. Tajfirouze , D. W. Savin

It has previously been argued that 1. spicules do not provide enough pre-heated plasma to fill the corona, and 2. even if they did, additional heating would be required to keep the plasma hot as it expands upward. We here address the…

Solar and Stellar Astrophysics · Physics 2015-06-17 Durgesh Tripathi , James A. Klimchuk

We use coronal imaging observations with SDO/AIA, and Hinode/EIS spectral data, to explore the potential of narrow band EUV imaging data for diagnosing the presence of hot (T >~5MK) coronal plasma in active regions. We analyze observations…

Solar and Stellar Astrophysics · Physics 2015-06-04 Paola Testa , Fabio Reale

Active region 11029 was a small, highly flare-productive solar active region observed at a time of extremely low solar activity. The region produced only small flares: the largest of the $>70$ Geostationary Observational Environmental…

Solar and Stellar Astrophysics · Physics 2015-05-14 M. S. Wheatland

Microflares are energetically smaller versions of solar flares, demonstrating the same processes of plasma heating and particle acceleration. However, it remains unclear down to what energy scales this impulsive energy release continues,…

Solar and Stellar Astrophysics · Physics 2024-02-09 Kristopher Cooper , Iain G. Hannah , Lindsay Glesener , Brian W. Grefenstette

We assess the possibility to detect the warm-hot intergalactic medium (WHIM) in emission and to characterize its physical conditions and spatial distribution through spatially resolved X-ray spectroscopy, in the framework of the recently…

The physics of solar flares occurring on the Sun is highly complex and far from fully understood. However, observations show that solar eruptions are associated with the intense kilogauss fields of active regions, where free energies are…

Solar and Stellar Astrophysics · Physics 2024-01-26 Bach Viet Do , Yang Chen , XuanLong Nguyen , Ward Manchester

The Atmospheric Imaging Assembly (AIA) telescope on board the Solar Dynamics Observatory (SDO) provides coronal EUV imaging over a broader temperature sensitivity range than the previous generations of instruments (EUVI, EIT, and TRACE).…

Solar and Stellar Astrophysics · Physics 2015-10-07 Federico A. Nuevo , Alberto M. Vásquez , Enrico Landi , Richard Frazin

We investigate the evolution of differential emission measure distribution (DEM[T]) in various phases of a B8.3 flare, which occurred on July 04, 2009. We analyze the soft X-ray (SXR) emission in 1.6-8.0 keV range, recorded collectively by…

Solar and Stellar Astrophysics · Physics 2016-06-08 Arun Kumar Awasthi , Barbara Sylwester , Janusz Sylwester , Rajmal Jain

Active region fan loops in AR 11076 were studied, in search of oscillations, using high cadence spectroscopic observations from EIS on board Hinode combined with imaging sequences from the AIA on board SDO. Spectra from EIS were analyzed in…

Solar and Stellar Astrophysics · Physics 2012-08-08 S. Krishna Prasad , D. Banerjee , Jagdev Singh

Real-world passive radiative cooling requires highly emissive, selective, and omnidirectional thermal emitters to maintain the radiative cooler at a certain temperature below the ambient temperature while maximizing the net cooling power.…

Applied Physics · Physics 2023-06-12 Yinan Zhang , Yinggang Chen , Tong Wang , Qian Zhu , Min Gu

We have measured mid-infrared (MIR) fluxes of 3C sources on images taken with ISOCAM onboard the Infrared Space Observatory (ISO). The photometric data were combined with existing photometry at other wavelengths to assemble the spectral…

Astrophysics · Physics 2009-11-10 Wolfram Freudling , Ralf Siebenmorgen

Most studies of high-mass star formation focus on massive luminous clumps, but the physical properties of their larger scale environment are poorly known. In this work, we aim at characterising the effects of clustered star formation and…

Astrophysics of Galaxies · Physics 2015-06-12 S. Leurini , F. Wyrowski , F. Herpin , F. van der Tak , R. Guesten , E. F. van Dishoeck

Context: Flux emergence in the solar atmosphere is a complex process that causes a release of magnetic energy as heat and acceleration of solar plasma at a variety of spatial scales. Methods: We analysed imaging spectropolarimetric data…