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The X-ray emission from the Sun reveals a very dynamic hot atmosphere, the corona, which is characterized by a complex morphology and broad range of timescales of variability and spatial structuring. The solar magnetic fields play a…

Solar and Stellar Astrophysics · Physics 2022-06-09 Paola Testa , Fabio Reale

Small-scale eruptions could play an important role in coronal heating, generation of solar energetic particles (SEPs), and mass source of the solar wind. However, they are poorly observed, and their characteristics, distributions, and…

Solar and Stellar Astrophysics · Physics 2024-10-24 Rui Wang , Ying D. Liu , Xiaowei Zhao , Huidong Hu

Arch-like loop structures filled with million Kelvin hot plasma form the building blocks of the quiet-Sun corona. Both high-resolution observations and magnetoconvection simulations show the ubiquitous presence of magnetic fields on the…

8000 images of the Solar corona were captured during the June 2001 total Solar eclipse. New software for the alignment of the images and an automated technique for detecting intensity oscillations using multi scale wavelet analysis were…

Astrophysics · Physics 2009-11-10 A. C. Katsiyannis , F. Murtagh

As a part of a study of the cause of solar coronal heating, we searched for high-frequency (~1 Hz) intensity oscillations in coronal loops in the [Fe XIV] coronal green line. We summarize results from observations made at the 11 August 1999…

Astrophysics · Physics 2015-06-24 Jay M. Pasachoff , Bryce A. Babcock , Kevin D. Russell , Daniel B. Seaton

The spectroscopic observations presented here were acquired during the 2017 August 21 total solar eclipse with a three-channel partially multiplexed imaging spectrometer (3PAMIS) operating at extremely high orders ($>$ 50). The 4 $R_\odot$…

Solar and Stellar Astrophysics · Physics 2024-03-18 Yingjie Zhu , Shadia R. Habbal , Adalbert Ding , Bryan Yamashiro , Enrico Landi , Benjamin Boe , Sage Constantinou , Michael Nassir

This article reports the analysis of a set of Fabry-Perot interferograms that were studied to probe the physical parameters of the inner solar corona. The observations were carried out in the coronal green line, Fe XIV 5302.86 {\AA}, during…

Solar and Stellar Astrophysics · Physics 2019-03-20 Maya Prabhakar , K. P. Raju , T. Chandrasekhar

Measurement of the coronal magnetic field is a crucial ingredient in understanding the nature of solar coronal phenomena at all scales. We employed STEREO/COR1 data obtained during a deep minimum of solar activity in February 2008…

Solar and Stellar Astrophysics · Physics 2014-05-06 M. Kramar , V. Airapetian , Z. Mikić , J. Davila

Data from recent numerical simulations of the solar corona and transition region are analysed and the magnetic field connection between the low corona and the photosphere is found to be close to that of a potential field. The fieldline to…

Astrophysics · Physics 2014-10-13 B. V. Gudiksen , Å. Nordlund

Observations of the Sun and of Sun-like stars provide access to different aspects of stellar magnetic activity that, when combined, help us piece together a more comprehensive picture than can be achieved from only the solar or the stellar…

Solar and Stellar Astrophysics · Physics 2010-12-14 Carolus J. Schrijver

Temporal variation of the solar coronal rotation appears to be very complex and its relevances to the eleven-year solar activity cycle are still unclear. Using the modified coronal index for the time interval from 1939 January 1 to 2019 May…

Solar and Stellar Astrophysics · Physics 2020-01-08 L. H. Deng , X. J. Zhang , H. Deng , Y. Mei , F. Wang

The activity of the Sun alternates between a solar minimum and a solar maximum, the former corresponding to a period of "quieter" status of the heliosphere. During solar minimum, it is in principle more straightforward to follow eruptive…

A sequence of apparently coupled eruptions was observed on 2010 August 1-2 by SDO and STEREO. The eruptions were closely synchronized with one another, even though some of them occurred at widely separated locations. In an attempt to…

Solar and Stellar Astrophysics · Physics 2015-06-11 V. S. Titov , Z. Mikic , T. Török , J. A. Linker , O. Panasenco

We present coordinated coronal observations of the August 21, 2017 total solar eclipse with the Airborne Infrared Spectrometer (AIR-Spec) and the Extreme-ultraviolet Imaging Spectrometer (EIS). These instruments provide an unprecedented…

Solar and Stellar Astrophysics · Physics 2019-08-07 Chad A. Madsen , Jenna E. Samra , Giulio Del Zanna , Edward E. DeLuca

Using a summary curve of two eigen vectors of solar magnetic field oscillations derived with Principal Components Analysis (PCA) from synoptic maps for solar cycles 21-24 as a proxy of solar activity, we extrapolate this curve backwards…

Solar and Stellar Astrophysics · Physics 2021-09-20 V. V. Zharkova , S. J. Shepherd , E. Popova , S. I Zharkov

The last solar minimum has been unusually quiet compared to the previous minima (since space-based radiometric measurements are available). The Sun's magnetic flux was substantially lower during this minimum. Some studies also show that the…

Solar and Stellar Astrophysics · Physics 2015-09-02 F. Shakeri , L. Teriaca , S. K. Solanki

We investigate the improved detection of extrasolar planets around eclipsing binaries using eclipse minima timing, and extrasolar moons around transiting planets using transit timing, offered by the upcoming COROT (ESA, 2005), Kepler (NASA,…

Astrophysics · Physics 2007-05-23 L. R. Doyle , H. J. Deeg

The goal of this paper is to understand the drivers, configurations, and scenarios of two similar eruptive events, which occurred in the same solar active region 9973 on 2002 June 1 and 2. The June 2 event was previously studied by Sui,…

Solar and Stellar Astrophysics · Physics 2009-08-28 N. S. Meshalkina , A. M. Uralov , V. V. Grechnev , A. T. Altyntsev , L. K. Kashapova

Magnetic loops filled with hot plasma are the main building blocks of the solar corona. Usually they have lengths of the order of the barometric scale height in the corona that is 50 Mm. Previously it has been suggested that miniature…

Solar and Stellar Astrophysics · Physics 2017-03-15 Krzysztof Barczynski , Hardi Peter , Sabrina L. Savage

Mid-term quasi-periodicities in solar coronal mass ejections (CMEs) during the most recent solar maximum cycle 23 are reported here for the first time using the four-year data (February 5, 1999 to February 10, 2003) of the Large Angle…

Astrophysics · Physics 2009-11-10 Y. -Q. Lou , Y. -M. Wang , Z. Fan , S. Wang , J. Wang