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UV bursts are transients in the solar atmosphere with an increased impulsive emission in the extreme UV lasting for one to several tens of minutes. They often show spectral profiles indicative of a bi-directional outflow in response to…

Solar and Stellar Astrophysics · Physics 2019-07-31 H. Peter , Y. -M. Huang , L. P. Chitta , P. R. Young

Coronal mass ejections (CMEs) are powerful drivers of space weather, with magnetic flux ropes (MFRs) widely regarded as their primary precursors. However, the variation in reconnection flux during the evolution of MFR during CME eruptions…

Solar and Stellar Astrophysics · Physics 2026-04-16 Samriddhi Sankar Maity , Piyali Chatterjee , Ranadeep Sarkar , Ijas S. Mytheen

Evidence for the emergence of twisted flux tubes into the solar atmosphere has, so far, come from indirect signatures. In this work, we investigate the topological input of twisted flux tube emergence directly by studying helicity and…

Solar and Stellar Astrophysics · Physics 2020-03-09 David MacTaggart , Chris Prior

Solar active regions are formed through the emergence of magnetic flux from the deeper convection zone. Recent satellite observations have shown that a horizontal divergent flow (HDF) stretches out over the solar surface just before the…

Solar and Stellar Astrophysics · Physics 2015-06-15 Shin Toriumi , Takaaki Yokoyama

Evidence of surface magnetism is now observed on an increasing number of cool stars. The detailed manner by which dynamo-generated magnetic fields giving rise to starspots traverse the convection zone still remains unclear. Some insight…

Solar and Stellar Astrophysics · Physics 2017-09-20 Maria A. Weber , Matthew K. Browning , Suzannah Boardman , Joshua Clarke , Samuel Pugsley , Edward Townsend

A standard model for eruptive flares aims at describing observational 3D features of the reconnecting coronal magnetic field. Extensions to the 2D model require the physical understanding of 3D reconnection processes at the origin of the…

Solar and Stellar Astrophysics · Physics 2015-06-16 Miho Janvier , Guillaume Aulanier , Etienne Pariat , Pascal Demoulin

Magnetic reconnection has been observed in the transition region of quasi-parallel shocks. In this work, the particle-in-cell method is used to simulate three-dimensional reconnection in a quasi-parallel shock. The shock transition region…

Space Physics · Physics 2022-09-07 J. Ng , L. -J. Chen , N. Bessho , J. Shuster , B. Burkholder , J. Yoo

We demonstrate that conservation of global helicity plays only a minor role in determining the nature and consequences of magnetic reconnection in the solar atmosphere. First, we show that observations of the solar coronal magnetic field…

Astrophysics · Physics 2015-06-24 Spiro K. Antiochos , C. Richard DeVore

Context. Some of the most dynamic active regions are associated with complex photospheric magnetic configurations such as quadrupolar regions, and especially ones with a $\delta$-spot configuration and a strong Polarity Inversion Line…

Solar and Stellar Astrophysics · Physics 2019-10-09 P. Syntelis , E. J. Lee , C. W. Fairbairn , V. Archontis , A. W. Hood

Two X-class solar flares occurred on 2017 September 6 from active region NOAA 12673: the first one is a confined X2.2 flare, and it is followed only $\sim 3$ hours later by the second one, which is the strongest flare in solar cycle 24,…

Solar and Stellar Astrophysics · Physics 2020-02-19 Peng Zou , Chaowei Jiang , Fengsi Wei , Xueshang Feng , Pingbing Zuo , Yi Wang

Starting from an exact, steady-state, force-free solution of the magnetohydrodynamic (MHD) equations, we investigate how resistive current layers are induced by perturbing line-tied three-dimensional magnetic equilibria. This is achieved by…

Solar and Stellar Astrophysics · Physics 2016-01-12 Frederic Effenberger , I. J. D. Craig

Magnetic reconnection is the key to explosive phenomena in the universe. The flux rope is crucial in three-dimensional magnetic reconnection theory and are commonly considered to be generated by secondary tearing mode instability. Here we…

Context. We introduce a model for including accelerated particles in pure magnetohydrodynamics (MHD) simulations of the solar atmosphere. Aims. We show that the method is viable and produces results that enhance the realism of MHD…

Solar and Stellar Astrophysics · Physics 2018-12-05 Helle Bakke , Lars Frogner , Boris Vilhelm Gudiksen

We present numerical simulations of active region scale flux emergence covering a time span of up to 6 days. Flux emergence is driven by a bottom boundary condition that advects a semi-torus of magnetic field with $1.7 \times 10^{22}$ Mx…

Solar and Stellar Astrophysics · Physics 2015-06-18 M. Rempel , M. C. M Cheung

The role of MHD turbulence in astrophysical environments is still highly debated. An important question that permeates this debate is the transport of magnetic flux. This is particularly important, for instance, in the context of star…

Solar flares and coronal mass ejections, the primary space weather disturbances affecting the entire heliosphere and near-Earth environment, mainly emanate from sunspot regions harbouring high degrees of magnetic twist. However, it is not…

Solar and Stellar Astrophysics · Physics 2023-06-01 Shin Toriumi , Hideyuki Hotta , Kanya Kusano

Magnetic reconnection is the key mechanism for energy release in solar eruptions, where the high-temperature emission is the primary diagnostic for investigating the plasma properties during the reconnection process. Non-thermal broadening…

Solar and Stellar Astrophysics · Physics 2022-11-15 Chengcai Shen , Vanessa Polito , Katharine K. Reeves , Bin Chen , Sijie Yu , Xiaoyan Xie

This work is devoted to study the magnetic reconnection instability under solar spicule conditions. Numerical study of the resistive tearing instability in a current sheet is presented by considering the magnetohydrodynamic (MHD) framework.…

Solar and Stellar Astrophysics · Physics 2014-06-30 Z. Fazel , H. Ebadi

We explore the structure of a dipole-type vacuum field of a slowly rotating magnetic star near the horizon of a supermassive black hole, where the structure of field lines becomes highly distorted by effects of strong gravity. Such a…

High Energy Astrophysical Phenomena · Physics 2018-12-13 Ondřej Kopáček , T. Tahamtan , Vladimír Karas

Solar flares are often associated with coronal eruptions, but there are confined ones without eruption, even for some X-class flares. How such large flares occurred and why they are confined are still not well understood. Here we studied a…

Solar and Stellar Astrophysics · Physics 2019-01-23 Peng Zou , Chaowei Jiang , Xueshang Feng , Pingbing Zuo , Yi Wang , Fengsi Wei