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Related papers: A Multi-Wavelength Statistical Study of Supra-Arca…

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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

Spectroscopic observations of a solar limb flare recorded by SUMER on SOHO reveal, for the first time, hot fast magnetic reconnection outflows in the corona. As the reconnection site rises across the SUMER spectrometer slit, significant…

Astrophysics · Physics 2018-06-19 Tongjiang Wang , Linhui Sui , Jiong Qiu

High resolution spectropolarimetric observations by Hinode reveal the existence of supersonic downflows at the umbra-penumbra boundary of 3 sunspots that was recently reported by Louis et al. (2010). These downflows are observed to be…

Solar and Stellar Astrophysics · Physics 2015-03-17 Rohan E. Louis , Luis R. Bellot Rubio , Shibu K. Mathew , P. Venkatakrishnan

In a previous work, we reported on the discovery of supersonic magnetic upflows on granular cells in data from the {\sc Sunrise}/IMaX instrument. In the present work we investigate the physical origin of these events employing data of the…

Solar and Stellar Astrophysics · Physics 2015-06-15 J. M. Borrero , V. Martinez Pillet , W. Schmidt , C. Quintero Noda , J. A. Bonet , J. C. del Toro Iniesta , L. R. Bellot Rubio

Using high spatial and temporal data from the \emph{Solar Dynamics Observatory} (\emph{SDO}) and the \emph{Interface Region Imaging Spectrograph} (\emph{IRIS}), several observational signatures of magnetic reconnection in the course of…

Solar and Stellar Astrophysics · Physics 2018-07-25 Bo Yang , Jiayan Yang , Yi Bi , Junchao Hong , Haidong Li , Zhe Xu , Hechao Chen

Recent numerical simulations and observations of sunspots show a significant amount of opposite polarity magnetic field within the sunspot penumbra. Most of the opposite polarity field is associated with convective downflows. We present an…

Solar and Stellar Astrophysics · Physics 2019-11-06 Lokesh Bharti , Matthias Rempel

Svestka (Solar Phys. 1989, 121, 399) on the basis of the Solar Maximum Mission observations introduced a new class of flares, the so-called flare hybrids. When they start, they look as typical compact flares (phase 1), but later on they…

Solar and Stellar Astrophysics · Physics 2015-05-20 M. Tomczak , P. Dubieniecki

Persistent outflows have recently been detected at boundaries of some active regions. Although these outflows are suggested to be possible sources of the slow solar wind, the nature of these outflows is poorly understood. Through an…

Solar and Stellar Astrophysics · Physics 2015-05-19 L. -J. Guo , H. Tian , J. -S. He

We measure the horizontal subsurface flow in a fast emerging active region (NOAA 11158) using the ring-diagram technique and the HMI high-spatial resolution Dopplergrams. This active region had a complex magnetic structure and displayed…

Solar and Stellar Astrophysics · Physics 2015-08-04 Kiran Jain , S. C. Tripathy , F. Hill

In this work, we study and quantify properties of strong-field small-scale convection and compare observed properties with those predicted by numerical simulations. We analyze spectropolarimetric 630.25 nm data from a unipolar ephemeral…

Solar and Stellar Astrophysics · Physics 2015-05-19 G. Narayan , G. B. Scharmer

Self-organization in continuous systems is associated with dissipative processes. In particular, for magnetized plasmas, it is known as magnetic relaxation, where the magnetic energy is converted into heat and kinetic energy of flow through…

Solar and Stellar Astrophysics · Physics 2024-01-23 Satyam Agarwal , Ramit Bhattacharyya , Shangbin Yang

Solar flares are transient yet dramatic events in the atmosphere of the Sun, during which a vast amount of magnetic energy is liberated. This energy is subsequently transported through the solar atmosphere or into the heliosphere, and…

Solar and Stellar Astrophysics · Physics 2022-12-14 Graham S. Kerr

We propose a physical mechanism to explain giant flares and radio afterglows in terms of a magnetospheric model containing both a helically twisted flux rope and a current sheet (CS). With the appearance of CS, we solve a mixed boundary…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Lei Huang , Cong Yu

A compact X-class flare on 2004-Feb-26 showed a concentrated source of hard X-rays at the tops of the flare's loops. This was analyzed in previous work (Longcope et al. 2010), and interpreted as plasma heated and compressed by slow…

Solar and Stellar Astrophysics · Physics 2016-12-28 Dana Longcope , Jiong Qiu , Jasmine Brewer

Post-flare loops are loop-like plasmas observed during the decay phase of solar flares, and they are expected to exist for stellar flares. However, it is unclear how post-flare loops are observed in stellar flares' cases. To clarify…

Solar and Stellar Astrophysics · Physics 2024-09-13 Takato Otsu , Ayumi Asai , Kai Ikuta , Kazunari Shibata

Magnetic reconnection plays a crucial role in powering solar flares, production of energetic particles, and plasma heating. However, where the magnetic reconnections occur, how and where the released magnetic energy is transported, and how…

Solar and Stellar Astrophysics · Physics 2020-09-02 Sijie Yu , Bin Chen , Katharine K. Reeves , Dale E. Gary , Sophie Musset , Gregory D. Fleishman , Gelu M. Nita , Lindsay Glesener

The arched field lines forming coronal arcades are often observed to undulate as magnetohydrodynamic (MHD) waves propagate both across and along the magnetic field. These waves are most likely a combination of resonantly coupled fast…

Solar and Stellar Astrophysics · Physics 2018-05-02 Bradley W. Hindman , Rekha Jain

The extreme space weather conditions resulting from high energetic events likes solar flares and Coronal Mass Ejections (CMEs) demand for reliable space weather forecasting. The magnetic flux tubes while rising through the convection zone…

Solar and Stellar Astrophysics · Physics 2022-10-19 B Lekshmi , Kiran Jain , Rudolf W. Komm , Dibyendu Nandy

Icing on three-dimensional wings causes severe flow separation near stall. Standard improved delayed detached eddy simulation (IDDES) is unable to correctly predict the separating reattaching flow due to its inability to accurately resolve…

Fluid Dynamics · Physics 2022-10-19 Maochao Xiao , Yufei Zhang , Feng Zhou

We studied the magnetic topology of active region 12158 on 2014 September 10 and compared it with the observations before and early in the flare which begins at 17:21 UT (SOL2014-09-10T17:45:00). Our results show that the sigmoidal…

Solar and Stellar Astrophysics · Physics 2016-06-01 Jie Zhao , Stuart A. Gilchrist , Guillaume Aulanier , Brigitte Schmieder , Etienne Pariat , Hui Li