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Coronal holes are the dark patches in the solar corona associated with relatively cool, less dense plasma and unipolar fields. The fast component of the solar wind emanates from these regions. Several observations reveal the presence of…

Solar and Stellar Astrophysics · Physics 2016-03-09 D. Banerjee , S. Krishna Prasad

Coronal cells are visible at temperatures of ~ 1.2 MK in Fe XII coronal images obtained from the Solar Dynamics Observatory (SDO) and Solar Terrestrial Relations Observatory (STEREO) spacecraft. We show that near a filament channel, the…

Solar and Stellar Astrophysics · Physics 2015-06-16 N. R. Sheeley, , S. F. Martin , O. Panasenco , H. P. Warren

The solar atmosphere shows anomalous variation in temperature, starting from the 5500 K photosphere to the million-degree Kelvin corona. The corona itself expands into the interstellar medium as the free streaming solar wind, which…

Solar and Stellar Astrophysics · Physics 2023-04-05 Vishal Upendran

This study investigates and compares brightness and area of coronal bright points (CBPs) inside and outside of coronal holes (CHs) using the single-dish Band 6 observations by the Atacama Large Millimeter/submillimeter Array (ALMA),…

Solar and Stellar Astrophysics · Physics 2023-02-22 F. Matković , R. Brajša , M. Temmer , S. G. Heinemann , H. -G. Ludwig , S. H. Saar , C. L. Selhorst , I. Skokić , D. Sudar

Solar corona is much hotter than lower layers of the solar atmosphere-photosphere and chromosphere. The coronal temperature is up to 1MK in quiet sun areas, while up to several MK in active regions, which implies a key role of magnetic…

Solar and Stellar Astrophysics · Physics 2025-06-24 Gregory D. Fleishman , Alexey A. Kuznetsov , Gelu M. Nita

The properties and spatial distribution of large-scale structures of the solar corona determine the observed solar wind structure at 1 au. Coronal holes are a major source of fast solar wind, an important geo-effective component, and appear…

Solar and Stellar Astrophysics · Physics 2026-03-27 K. H. P. Henadhira Arachchige , B. Perri , A. S. Brun

Coronal holes (CHs) are regions with unbalanced magnetic flux, and have been associated with open magnetic field (OMF) structures. However, it has been reported that some CHs do not intersect with OMF regions. To investigate the…

Solar and Stellar Astrophysics · Physics 2022-07-27 Guan-Han Huang , Chia-Hsien Lin , Lou-Chuang Lee

We use Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) data to reconstruct the plasma properties from differential emission measure (DEM) analysis for a previously studied long-lived, low-latitude coronal hole (CH) over…

Solar and Stellar Astrophysics · Physics 2020-01-15 Jonas Saqri , Astrid M. Veronig , Stephan G. Heinemann , Stefan J. Hofmeister , Manuela Temmer , Karin Dissauer , Yang Su

Magnetic field diagnostics of the transition region from the chromosphere to the corona faces us with the problem that one has to apply extreme UV spectro-polarimetry. While for coronal diagnostic techniques already exist through infrared…

Solar and Stellar Astrophysics · Physics 2013-03-11 H. Peter

We developed an automated procedure for the identification of transient brightenings in images from the X-ray telescope on-board Hinode taken with an Al Poly filter in the equatorial coronal holes, polar coronal holes, and the quiet Sun…

Solar and Stellar Astrophysics · Physics 2015-05-18 S. Subramanian , M. S. Madjarska , J. G. Doyle

We describe a method for the automatic mapping of coronal holes (CH) using simultaneous multi-instrument EUV imaging data. Synchronized EUV images from STEREO/EUVI A&B 195A and SDO/AIA 193A are preprocessed, including PSF deconvolution and…

Solar and Stellar Astrophysics · Physics 2016-05-26 R. M. Caplan , C. Downs , J. L. Linker

With the data from the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO), we present a magnetic interaction between an isolated coronal hole (CH) and an emerging…

Solar and Stellar Astrophysics · Physics 2015-06-17 L. Ma , Z. Q. Qu , X. L. Yan , Z. K. Xue

Global magnetic field models use as input synoptic data, which usually show "aging effects" as the longitudinal 360{\deg} information is not obtained simultaneously. Especially during times of increased solar activity, the evolution of the…

Solar and Stellar Astrophysics · Physics 2021-10-04 Stephan G. Heinemann , Manuela Temmer , Stefan J. Hofmeister , Aleksandar Stojakovic , Laurent Gizon , Dan Yang

A new method for automated detection of polar coronal holes is presented. This method, called perimeter tracing, uses a series of 171, 195, and 304 \AA\ full disk images from the Extreme ultraviolet Imaging Telescope (EIT) on SOHO over…

Solar and Stellar Astrophysics · Physics 2015-05-13 Michael S. Kirk , W. Dean Pesnell , C. Alex Young , Shea A. Hess Webber

Solar corona, the last main layer of the atmosphere of the Sun, is detectable in the EUV and X-ray. The corona is expanding into space up to millions of kilometers and is observable during the eclipse. The temperature is increasing about…

Solar and Stellar Astrophysics · Physics 2019-04-02 Najmeh Ahmadi , Shervin Parsi

We investigate the evolution of a well-observed, long-lived, low-latitude coronal hole (CH) over 10 solar rotations in the year 2012. By combining EUV imagery from STEREO-A/B and SDO we are able to track and study the entire evolution of…

Solar and Stellar Astrophysics · Physics 2018-08-01 S. G. Heinemann , M. Temmer , S. J. Hofmeister , A. M. Veronig , S. Vennerstroem

Central supermassive black holes of active galactic nuclei host hot plasma with a temperature of $10^9$ K, namely coronae. Like the Sun, black hole coronae are theoretically believed to be heated by their magnetic activity, which have never…

High Energy Astrophysical Phenomena · Physics 2018-12-26 Yoshiyuki Inoue , Akihiro Doi

We developed a new numerical code that is able to perform 2.5D simulations of a magnetohydrodynamic (MHD) wave propagation in the corona, and its interaction with a low density region, such as a coronal hole (CH). We show that the impact of…

The recent analysis of observations taken with the EIS instrument on Hinode suggests that well constrained measurements of the temperature distribution in solar active regions can finally be made. Such measurements are critical for…

Solar and Stellar Astrophysics · Physics 2015-06-04 Harry P. Warren , Amy R. Winebarger , David H. Brooks

The heating of the solar chromosphere and corona to the observed high temperatures, imply the presence of ongoing heating that balances the strong radiative and thermal conduction losses expected in the solar atmosphere. It has been…