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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

Recent observations from the Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode have shown that low density areas on the periphery of active regions are characterized by strong blue-shifts at 1 MK. These Doppler shifts have been…

Solar and Stellar Astrophysics · Physics 2015-05-19 Ignacio Ugarte-Urra , Harry P. Warren

We report multi-wavelength ultraviolet observations taken with the IRIS satellite, concerning the emergence phase in the upper chromosphere and transition region of an emerging flux region (EFR) embedded in the unipolar plage of active…

Solar and Stellar Astrophysics · Physics 2019-07-17 S. L. Guglielmino , F. Zuccarello , P. R. Young , P. Romano , M. Murabito

We present new measurements of the dependence of the Extreme Ultraviolet radiance on the total magnetic flux in active regions as obtained from the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager on board the…

Solar and Stellar Astrophysics · Physics 2017-09-20 Ignacio Ugarte-Urra , Harry P. Warren , Lisa A. Upton , Peter R. Young

Penumbral transient brightening events have been attributed to magnetic reconnection episodes occurring in the low corona. We investigated the trigger mechanism of these events in active region NOAA 12546 by using multi-wavelength…

Solar and Stellar Astrophysics · Physics 2020-02-26 M. Murabito , S. L. Guglielmino , I. Ermolli , M. Stangalini , F. Giorgi

Multiwavelength observations of the propagating disturbances (PDs), discovered by Atmospheric Imaging Assembly (AIA) onboard Solar Dynamics Observatory (SDO), are analyzed to determine its driving mechanism and physical nature. Two magnetic…

The Sun's corona is millions of degrees hotter than its 5,000 K photosphere. This heating enigma is typically addressed by invoking the deposition at coronal heights of non-thermal energy generated by the interplay between convection and…

Solar and Stellar Astrophysics · Physics 2009-08-11 Bart De Pontieu , Scott W. McIntosh , Viggo H. Hansteen , Carolus J. Schrijver

A comprehensive understanding of the structure of Doppler motions in transition region including the center-to-limb variation and its relationship with the magnetic field structure is vital for the understanding of mass and energy transfer…

Solar and Stellar Astrophysics · Physics 2020-01-08 Avyarthana Ghosh , James A. Klimchuk , Durgesh Tripathi

A magnetic channel - a series of polarity reversals separating elongated flux threads with opposite polarities - may be a manifestation of a highly non-potential magnetic configuration in active regions. To understand its formation we have…

Solar and Stellar Astrophysics · Physics 2015-05-19 Eun-Kyung Lim , Jongchul Chae , Ju Jing , Haimin Wang , Thomas Wiegelmann

We compare the small-scale features visible in the Ne viii Doppler-shift map of an equatorial coronal hole (CH) as observed by SUMER with the small-scale structures of the magnetic field as constructed from a simultaneous photospheric…

Astrophysics · Physics 2009-06-25 T. Wiegelmann , L. D. Xia , E. Marsch

Flares and eruptions from solar active regions are associated with atmospheric electrical currents accompanying distortions of the coronal field away from a lowest-energy potential state. In order to better understand the origin of these…

Solar and Stellar Astrophysics · Physics 2016-04-06 C. J. Schrijver

Solar flares are sudden and violent releases of magnetic energy in the solar atmosphere that can be divided in eruptive flares, when plasma is ejected from the solar atmosphere, resulting in a coronal mass ejection (CME), and confined…

Solar and Stellar Astrophysics · Physics 2017-05-24 F. P. Zuccarello , R. Chandra , B. Schmieder , G. Aulanier , R. Joshi

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

We determine magnetic fields from the photosphere to the upper chromosphere combining data from the Hinode satellite and the CLASP2.1 sounding rocket experiment. CLASP2.1 provided polarization profiles of the Mg~{|sc ii} $h$ and $k$ lines,…

We report multi-wavelength ultraviolet observations taken with the IRIS satellite, concerning the emergence phase in the upper chromosphere and transition region of an emerging flux region (EFR) embedded in the pre-existing field of active…

Solar and Stellar Astrophysics · Physics 2018-04-18 Salvo L. Guglielmino , Francesca Zuccarello , Peter R. Young , Mariariata Murabito , Paolo Romano

Solar active region (AR) 11283 is a very magnetically complex region and it has produced many eruptions. However, there exists a non-eruptive filament in the plage region just next to an eruptive one in the AR, which gives us an opportunity…

Solar and Stellar Astrophysics · Physics 2016-01-20 Chaowei Jiang , S. T. Wu , Xueshang Feng , Qiang Hu

A statistical study has been carried out of the relationship between plasma flow Doppler velocities and magnetic field parameters during the emergence of active regions at the solar photospheric level with data acquired by the Michelson…

Solar and Stellar Astrophysics · Physics 2017-05-01 A. Khlystova

Context: Solar active regions (ARs) are key manifestations of the Sun's magnetic activity, displaying diverse spatial and temporal characteristics. Their formation and evolution play a crucial role in understanding the solar dynamo and…

Solar and Stellar Astrophysics · Physics 2025-08-06 M. Švanda , J. Jurčák , M. Schmassmann

Solar quiet- and coronal-hole region coronal jets frequently clearly originate from erupting minifilaments, but active-region jets often lack an obvious erupting-minifilament source. We observe a coronal-jet-productive active region (AR),…

Solar and Stellar Astrophysics · Physics 2023-10-24 Alphonse C. Sterling , Ronald L. Moore , Navdeep K. Panesar

A model of supra-arcade downflows (SADs), dark low density regions also known as tadpoles that propagate sunward during solar flares, is presented. It is argued that the regions of low density are flow channels carved by sunward-directed…

Space Physics · Physics 2015-06-16 P. A. Cassak , J. F. Drake , J. T. Gosling , T. -D. Phan , M. A. Shay , L. S. Shepherd
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