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The solar corona is orders of magnitude hotter than the underlying photosphere, but how the corona attains such high temperatures is still not understood. Soft X-ray (SXR) emission provides important diagnostics for thermal processes in the…

Solar and Stellar Astrophysics · Physics 2015-09-15 Amir Caspi , Thomas N. Woods , Harry P. Warren

Recent spectroscopic observations have revealed the ubiquitous presence of blueward asymmetries of emission lines formed in the solar corona and transition region. These asymmetries are most prominent in loop footpoint regions, where a…

Solar and Stellar Astrophysics · Physics 2011-08-11 Hui Tian , Scott W. McIntosh , Bart De Pontieu , Juan Martinez-Sykora , Marybeth Sechler , Xin Wang

Recent observations from Parker Solar Probe have revealed that the solar wind has a highly variable structure. How this complex behaviour is formed in the solar corona is not yet known, since it requires omnipresent fluctuations, which…

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

We used data from the Helioseismic and Magnetic Imager (HMI), and Atmospheric Imaging Assembly (AIA) on the \textit{Solar Dynamics Observatory} (SDO) to study coronal loops at small scales, emerging in the quiet Sun. With HMI line-of-sight…

Solar and Stellar Astrophysics · Physics 2013-04-15 LP. Chitta , R. Kariyappa , A. A. van Ballegooijen , E. E. DeLuca , S. S. Hasan , A. Hanslmeier

In previous studies a very hot plasma component has been diagnosed in solar active regions through the images in three different narrow-band channels of SDO/AIA. This diagnostic from EUV imaging data has also been supported by the matching…

Solar and Stellar Astrophysics · Physics 2015-06-18 A. Petralia , F. Reale , P. Testa , G. Del Zanna

Solar extreme-ultraviolet (EUV) lines emitted by highly charged ions have been extensively studied to discuss the issue of coronal heating and solar wind acceleration. Based on observations of the polar corona by the SUMER/SOHO…

Solar and Stellar Astrophysics · Physics 2015-06-22 G. Q. Zhao , D. J. Wu , C. B. Wang

Sky models have been used in the past to calibrate individual low radio frequency telescopes. Here we generalize this approach from a single antenna to a two element interferometer and formulate the problem in a manner to allow us to…

Instrumentation and Methods for Astrophysics · Physics 2017-06-28 Divya Oberoi , Rohit Sharma , Alan E. E. Rogers

The Sun is the most studied of all stars. It is a reference for all other observed stars and a laboratory of fundamental physics helping us understand processes occuring in conditions irreproducible on Earth. However, our understanding of…

This paper reviews our growing understanding of the physics behind coronal heating (in open-field regions) and the acceleration of the solar wind. Many new insights have come from the last solar cycle's worth of observations and theoretical…

Solar and Stellar Astrophysics · Physics 2010-02-02 Steven R. Cranmer , John L. Kohl , Mari Paz Miralles , Adriaan A. van Ballegooijen

Using the 2004 Venus transit of the Sun to constrain a semi-empirical point-spread function for the TRACE EUV solar telescope, we have measured the effect of stray light in that telescope. We find that 43% of 171A EUV light that enters…

Astrophysics · Physics 2011-02-11 C. E. DeForest , P. C. H. Martens , M. J. Wills-Davey

With the development of new instrumentation providing measurements of solar photospheric vector magnetic fields, we need to develop our understanding of the effects of current density on coronal magnetic field configurations. The object is…

Astrophysics · Physics 2009-11-13 S. Regnier , E. R. Priest

The quiet solar corona consists of myriads of loop-like features, with magnetic fields originating from network and internetwork regions on the solar surface. The continuous interaction between these different magnetic patches leads to…

Solar and Stellar Astrophysics · Physics 2021-04-13 L. P. Chitta , H. Peter , P. R. Young

Global coronal models seek to produce an accurate physical representation of the Sun's atmosphere which can be used, for example, to drive space weather models. Assessing their accuracy is a complex task and there are multiple observational…

The elemental composition of the Sun's hot atmosphere, the corona, shows a distinctive pattern that is different than the underlying surface, or photosphere (Pottasch 1963). Elements that are easy to ionize in the chromosphere are enhanced…

Solar and Stellar Astrophysics · Physics 2022-05-18 David H. Brooks , Deborah Baker , Lidia van Driel-Gesztelyi , Harry P. Warren , Stephanie L. Yardley

The Soft X-ray intensity of loops in active region cores and corresponding footpoint, or moss, intensity observed in the EUV remain steady for several hours of observation. The steadiness of the emission has prompted many to suggest that…

Astrophysics · Physics 2009-11-13 A. R Winebarger , H. P. Warren , D. A. Falconer

Coronal loops are plasma structures in the solar atmosphere with temperatures reaching millions of Kelvin, shaped and sustained by the magnetic field. However, their morphology and fundamental nature remain subjects of debate. By studying…

Solar and Stellar Astrophysics · Physics 2026-01-14 N. Vasantharaju , H. Peter , L. P. Chitta , S. Mandal

Understanding the solar corona requires knowledge of its dynamics through its various layers and subsequent connectivity to the heliosphere. This requires understanding the nature of the outflows and the physical transitions through the…

Solar and Stellar Astrophysics · Physics 2023-03-29 Nathalia Alzate , Huw Morgan , Simone Di Matteo

Long-term trends in the solar spectral irradiance are important to determine the impact on Earth's climate. These long-term changes are thought to be caused mainly by changes in the surface area covered by small-scale magnetic elements. The…

Solar and Stellar Astrophysics · Physics 2015-05-14 N. Afram , Y. C. Unruh , S. K. Solanki , M. Schuessler , S. K. Mathew

Coronal holes are the observational manifestation of the solar magnetic field open to the heliosphere and are of pivotal importance for our understanding of the origin and acceleration of the solar wind. Observations from space missions…