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To adequately constrain the frequency of energy deposition in active region cores in the solar corona, systematic comparisons between detailed models and observational data are needed. In this paper, we describe a pipeline for forward…

Solar and Stellar Astrophysics · Physics 2019-07-31 W. T. Barnes , S. J. Bradshaw , N. M. Viall

An enhancement in high-frequency acoustic power is commonly observed in the solar photosphere and chromosphere surrounding magnetic active regions. We perform 3D linear forward wave modelling with a simple wavelet pulse acoustic source to…

Solar and Stellar Astrophysics · Physics 2015-06-23 Carlos Rijs , Hamed Moradi , Damien Przybylski , Paul S. Cally

The emergence of active regions (ARs) leads to various dynamic activities. Using high-resolution and long-lasting H$\alpha$ observations from the New Vacuum Solar Telescope, we report the dynamics of NOAA AR 12700 in its emerging phase on…

Solar and Stellar Astrophysics · Physics 2019-09-06 Sihui Zhong , Yijun Hou , Jun Zhang

We studied 101 flux emergence events ranging from small ephemeral regions to large emerging flux regions which were observed with Hinode Solar Optical Telescope filtergram. We investigated how the total magnetic flux of the emergence event…

Solar and Stellar Astrophysics · Physics 2015-05-28 Kenichi Otsuji , Reizaburo Kitai , Kiyoshi Ichimoto , Kazunari Shibata

Emerging dimming occurs in isolated solar active regions (ARs) during the early stages of magnetic flux emergence. Observed by the Atmospheric Imaging Assembly, it features a rapid decrease in extreme-ultraviolet (EUV) emission in the 171…

Solar and Stellar Astrophysics · Physics 2021-05-05 Anna V. Payne , Xudong Sun

I report observations of unusually strong photospheric and chromospheric velocity oscillations in and near the leading sunspot of NOAA 10781 on 03 July 2005. I investigate an impinging wave as a possible origin of the velocity pattern, and…

Solar and Stellar Astrophysics · Physics 2015-03-17 C. Beck

We present multi-wavelength observations of a fan-spine dome in the active region NOAA 11996 with the \textit{Interface Region Imaging Spectrograph} (IRIS) and the Atmospheric Imaging Assembly on board the \textit{Solar Dynamics…

Solar and Stellar Astrophysics · Physics 2015-05-11 Fayu Jiang , Jun Zhang , Shuhong Yang

The physical conditions leading the sunspot penumbra decay are poorly understood so far. We investigate the photospheric magnetic and velocity properties of a sunspot penumbra during the decay phase to advance the current knowledge of the…

Solar and Stellar Astrophysics · Physics 2021-09-15 M. Murabito , S. L. Guglielmino , I. Ermolli , P. Romano , S. Jafarzadeh , L. H. M. Rouppe van der Voort

We present a multiwavelength study of the formation and ejection of a plasma blob and associated EUV waves in AR NOAA 11176, observed by SDO/AIA and STEREO on 25 March 2011. SDO/AIA images clearly show the formation and ejection of a plasma…

Solar and Stellar Astrophysics · Physics 2015-06-15 Pankaj Kumar , P. K. Manoharan

The dynamics of magnetic fields in the Sun's active regions plays a key role in triggering solar eruptions. Studies have shown that changes in the photosphere's magnetic field can destabilize large-scale structure of the corona, leading to…

Solar and Stellar Astrophysics · Physics 2025-03-25 Partha Chowdhury , Belur Ravindra , Sanjiv Kumar Tiwari

While the {\it Helioseismic and Magnetic Imager} (HMI) onboard the {\it Solar Dynamics Observatory} (SDO) provides Doppler velocity [$V$], continuum intensity [$I_C$], and line-depth [$Ld$] observations, each of which is sensitive to the…

Solar and Stellar Astrophysics · Physics 2015-09-24 Rachel Howe , Kiran Jain , Richard S. Bogart , Deborah A. Haber , Charles S. Baldner

Using Doppler velocity data from the SOI/MDI instrument onboard the SoHO spacecraft, we do time-distance helioseismic inversions for sound-speed perturbations beneath 16 sunspots observed in high-resolution mode. We clearly detect ring-like…

Astrophysics · Physics 2011-02-11 S. Couvidat , S. P. Rajaguru

The magnetic non-potentiality is important for understanding flares and other solar activities in active regions (ARs). Five non-potential parameters, i.e., electric current, current helicity, source field, photospheric free energy, and…

Solar and Stellar Astrophysics · Physics 2015-06-11 Qiao Song , Jun Zhang , Shuhong Yang , Yang Liu

In this study, we present the investigation of eleven recurring solar jets originated from two different sites (site 1 and site 2) close to each other (~ 11 Mm) in the NOAA active region (AR) 12035 during 15--16 April 2014. The jets were…

Solar and Stellar Astrophysics · Physics 2017-11-15 R. Joshi , B. Schmieder , R. Chandra , G. Aulanier , F. P. Zuccarello , W. Uddin

The use of acoustic holography in the high-frequency $p$-mode spectrum can resolve the source distributions of enhanced acoustic emissions within halo structures surrounding active regions. In doing so, statistical methods can then be…

Solar and Stellar Astrophysics · Physics 2015-08-06 Chris S. Hanson , Alina C. Donea , K. D. Leka

In previous works we introduced a nonlinear force-free method that self-consistently calculates the instantaneous budgets of free magnetic energy and relative magnetic helicity in solar active regions (ARs). Calculation is expedient and…

Solar and Stellar Astrophysics · Physics 2015-06-16 Kostas Tziotziou , Manolis K. Georgoulis , Yang Liu

Context. Observations of many active regions show a slow systematic outflow/upflow from their edges lasting from hours to days. At present no physical explanation has been proven, while several suggestions have been put forward. Aims. This…

Solar and Stellar Astrophysics · Physics 2021-08-25 K. Galsgaard , M. S. Madjarska , K. Vanninathan , Z. Huang , M. Presmann

Using the data on magnetic field maps and continuum intensity for Solar Cycles 23 and 24, we explored 100 active regions (ARs) that produced M5.0 or stronger flares. We focus on the presence/absence of the emergence of magnetic flux in…

Solar and Stellar Astrophysics · Physics 2024-02-29 Alexander S. Kutsenko , Valentina I. Abramenko , Andrei A. Plotnikov

We analyze data from Hinode spacecraft taken over two 54-minute periods during the emergence of AR 11024. We focus on small-scale portions within the observed solar active region and discover the appearance of very distinctive small-scale…

Solar and Stellar Astrophysics · Physics 2015-03-13 S. Vargas Dominguez , L. van Driel-Gesztelyi , L. R. Bellot Rubio , .

We investigate deviations in the mean phase travel time of acoustic waves preceding the emergence of 46 large active regions observed by the Helioseismic and Magnetic Imager (HMI). In our investigation, we consider two different procedures…

Solar and Stellar Astrophysics · Physics 2023-05-03 John Stefan , Alexander Kosovichev
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