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We report on three-dimensional (3D) MHD simulations of recurrent mini CME-like eruptions in a small active region (AR), which is formed by the dynamical emergence of a twisted (not kink unstable) flux tube from the solar interior. The…

Solar and Stellar Astrophysics · Physics 2014-05-28 V. Archontis , A. W. Hood , K. Tsinganos

We performed a systematic study of 12 active regions (ARs) with a broad range of areas, magnetic flux and associated solar activity in order to determine whether there are upflows present at the AR boundaries and if these upflows exist,…

Solar and Stellar Astrophysics · Physics 2021-06-16 S. L. Yardley , D. H. Brooks , D. Baker

We investigate the coronal magnetic energy and helicity budgets of ten solar ARs, around the times of large flares. In particular, we are interested in a possible relation of the derived quantities to the particular type of the flares that…

Solar and Stellar Astrophysics · Physics 2021-09-15 Manu Gupta , J. K. Thalmann , A. M. Veronig

Magnetic flux ropes (FRs) are twisted structures appearing on the sun, predominantly in the magnetically concentrated regions. These structures appear as coronal features known as filaments or prominences in H$\alpha$ observations, and as…

Solar and Stellar Astrophysics · Physics 2024-10-04 P. Vemareddy

Photospheric vector magnetograms from Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory are utilized as the boundary conditions to extrapolate both non-linear force-free and potential magnetic fields in solar corona.…

Solar and Stellar Astrophysics · Physics 2015-06-19 J. T. Su , J. Jing , S. Wang , T. Wiegelmann , H. M. Wang

Until now, how the magnetic fields in M/X-class flaring active regions (ARs) differ from C-class flaring ARs remains unclear. Here, we calculate the key magnetic field parameters within the area of high photospheric free energy density (HED…

Solar and Stellar Astrophysics · Physics 2024-03-01 Ting Li , Yanfang Zheng , Xuefeng Li , Yijun Hou , Xuebao Li , Yining Zhang , Anqin Chen

Vortex-flows exist across a broad range of spatial and temporal scales in the solar atmosphere. Small-scale vortices have been proposed to play an important role in energy transport in the solar atmosphere. However, their physical…

Solar and Stellar Astrophysics · Physics 2021-01-04 Nitin Yadav , Robert H. Cameron , Sami K. Solanki

Solar flares are highly energetic events that happen in the solar atmosphere. They are mostly observed as X-ray or gamma-ray bursts located on the Sun's surface. While they are known to be sites of particle acceleration, the acceleration…

Solar and Stellar Astrophysics · Physics 2023-10-25 Jonathan Mauro , Gwenhaël de Wasseige

A statistical analysis of the relationship between solar energetic particles (SEPs) and properties of solar flares and coronal mass ejections (CMEs) is presented. SEP events during solar cycle 23 are selected which are associated with solar…

Solar and Stellar Astrophysics · Physics 2014-12-18 M. Dierckxsens , K. Tziotziou , S. Dalla , I. Patsou , M. S. Marsh , N. B. Crosby , O. Malandraki , G. Tsiropoula

We study the effect of newly emerged solar active regions (ARs) on the large-scale magnetic environment of pre-existing ARs (PEARs). We first present a theoretical approach to quantify the "interaction energy" between new ARs and PEARs as…

Solar and Stellar Astrophysics · Physics 2016-06-09 Yixing Fu , Brian T. Welsch

Using the potential of two unprecedented missions, STEREO and RHESSI, we study three well observed fast CMEs that occurred close to the limb together with their associated high energy flare emissions in terms of RHESSI HXR spectra and flux…

Solar and Stellar Astrophysics · Physics 2015-05-18 M. Temmer , A. M. Veronig , E. P. Kontar , S. Krucker , B. Vrsnak

Solar coronal mass ejections (CMEs) show a large variety in their kinematic properties. CMEs originating in active regions and accompanied by strong flares are usually faster and accelerated more impulsively than CMEs associated with…

Astrophysics · Physics 2007-10-11 T. Toeroek , B. Kliem

Using a recently suggested magneto-morphological classification (MMC, Abramenko, 2021, MNRAS Vol 507) of solar active regions (ARs), we explored 3048 ARs, observed from12 May 1996 to 27 December 2021. Magnetograms were acquired with the…

Solar and Stellar Astrophysics · Physics 2026-01-21 Anastasiya Zhukova , Valentina Abramenko

It is well established that magnetic free energy associated with electric currents powers solar flares and coronal mass ejections (CMEs) from solar active regions (ARs). However, the conditions that determine whether an AR will produce an…

Solar and Stellar Astrophysics · Physics 2020-04-29 Ellis A. Avallone , Xudong Sun

Solar flares are rapid energy release phenomena that appear as bright ribbons in the chromosphere and high-temperature loops in the corona, respectively. Supra-arcade Downflows (SADs) are plasma voids that first come out above the flare…

Solar and Stellar Astrophysics · Physics 2021-07-21 Z. F. Li , X. Cheng , M. D. Ding , Katharine K. Reeves , DeOndre Kittrell , Mark Weber , David E. McKenzie

A statistical study of 77 solar active regions (ARs) is conducted to investigate the existence of identifiable correlations between the subsurface structural disturbances and the activity level of the active regions. The disturbances…

Solar and Stellar Astrophysics · Physics 2015-12-23 Chia-Hsien Lin

All three components of the current density are required to compute the heating rate due to free magnetic energy dissipation. Here we present a first test of a new model developed to determine if the times of increases in the resistive…

Solar and Stellar Astrophysics · Physics 2020-04-29 Michael L. Goodman , Chiman Kwan , Bulent Ayhan , Eric L. Shang

The origin of the slow solar wind is still an open issue. It has been suggested that upflows at the edge of active regions (AR) can contribute to the slow solar wind. Here, we compared the upflow region and the AR core and studied how the…

Solar and Stellar Astrophysics · Physics 2021-08-04 Krzysztof Barczynski , Louise Harra , Lucia Kleint , Brandon Panos , David H. Brooks

Sunspots or active regions (ARs) with a delta-magnetic configuration are known to be associated with strong eruptions such as flares and mass ejections. This article investigates the relationship between delta-ARs and flares over the course…

Solar and Stellar Astrophysics · Physics 2025-10-28 Rohan E. Louis

Solar active regions (ARs) are the main sources of flares and coronal mass ejections (CMEs). NOAA AR 12089, which emerged on 2014 June 10, produced two C-class flares accompanied by CMEs within five hours after its emergence. When producing…

Solar and Stellar Astrophysics · Physics 2024-10-02 Hanzhao Yang , Lijuan Liu