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Twisted magnetic fields should be ubiquitous in flare-producing active regions where the magnetic fields are strongly non-potential. It has been shown that reconnection in helical magnetic coronal loops results in plasma heating and…

Solar and Stellar Astrophysics · Physics 2016-01-20 R. F. Pinto , M. Gordovskyy , P. K. Browning , N. Vilmer

We analyze multi-wavelength data of a M7.9/1N class solar flare which occurred on 27 April, 2006 from AR NOAA 10875. GOES soft X-ray images provide the most likely signature of two interacting loops and their reconnection, which triggers…

Solar and Stellar Astrophysics · Physics 2015-05-19 Pankaj Kumar , A. K. Srivastava , B. V. Somov , P. K. Manoharan , R. Erdelyi , Wahab Uddin

A sample of Nobeyama flares was selected and analyzed using loop model for important flare parameters. The model for the flaring region consists of a three dimensional dipolar magnetic field, and spatial distributions of non-thermal…

Solar and Stellar Astrophysics · Physics 2015-06-16 Joaquim E. R. Costa , Paulo J. A. Simões , Tereza S. N. Pinto , Victor F. Melnikov

Magnetic reconnection is believed to be the prime mechanism to trigger solar flares and accelerate electrons up to energies of MeV. In the classical two-dimensional reconnection model, the separation motion of chromospheric ribbons…

Solar and Stellar Astrophysics · Physics 2011-02-11 Chang Liu , Haimin Wang

This Letter is to investigate the physics of a newly discovered phenomenon -- contracting flare loops in the early phase of solar flares. In classical flare models, which were constructed based on the phenomenon of expansion of flare loops,…

Astrophysics · Physics 2009-11-13 Jinhua Shen , Tuanhui Zhou , Haisheng Ji , Na Wang , Wenda Cao , Haimin Wang

The asymmetry in hard X-ray (HXR) emission at the footpoints (FPs) of flare loops is a ubiquitous feature closely associated with nonthermal electron transport. We analyze the asymmetric HXR radiation at two flare ribbons which is…

Solar and Stellar Astrophysics · Physics 2024-07-19 Guanglu Shi , Li Feng , Jun Chen , Beili Ying , Shuting Li , Qiao Li , Hui Li , Ying Li , Kaifan Ji , Yu Huang , Weiqun Gan , the LST team

A number of double coronal X-ray sources have been observed during solar flares by RHESSI, where the two sources reside at different sides of the inferred reconnection site. However, where and how are these X-ray-emitting electrons…

Solar and Stellar Astrophysics · Physics 2022-07-20 Xiangliang Kong , Jing Ye , Bin Chen , Fan Guo , Chengcai Shen , Xiaocan Li , Sijie Yu , Yao Chen , Joe Giacalone

A novel method of using hard X-rays as a diagnostic for chromospheric density and magnetic structures is developed to infer sub-arcsecond vertical variation of magnetic flux tube size and neutral gas density.Using Reuven Ramaty High Energy…

Astrophysics · Physics 2009-11-13 E. P. Kontar , I. G. Hannah , A. L. MacKinnon

We investigate two microflares of GOES classes A9 and C1 (after background subtraction) observed by STIX onboard Solar Orbiter with exceptionally strong nonthermal emission. We complement the hard X-ray imaging and spectral analysis by STIX…

Solar and Stellar Astrophysics · Physics 2024-03-12 Jonas Saqri , Astrid M. Veronig , Andrea Francesco Battaglia , Ewan C. M. Dickson , Dale E. Gary , Säm Krucker

The aim of the present paper is to use quasi-periodic oscillations in hard X-rays (HXRs) of solar flares as a diagnostic tool for investigation of impulsive electron acceleration. We have selected a number of flares which showed…

Solar and Stellar Astrophysics · Physics 2015-05-13 J. Jakimiec , M. Tomczak

In previous works we have developed a method to convert solar X-ray data, collected with the Yohkoh/SXT, into templates of stellar coronal observations. Here we apply the method to several solar flares, for comparison with stellar X-ray…

Astrophysics · Physics 2009-11-06 F. Reale , G. Peres , S. Orlando

We use data at 131, 171, and 304 A from the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory (SDO) to search for hot flux ropes in 141 M-class and X-class solar flares that occurred at solar longitudes equal to or…

Solar and Stellar Astrophysics · Physics 2015-08-06 A. Nindos , S. Patsourakos , A. Vourlidas , C. Tagikas

Non-thermal and thermal parameters of 85 solar flares of GOES class B1 to M6 (background subtracted classes A1 to M6) have been compared to each other. The hard X-ray flux has been measured by RHESSI and a spectral fitting provided flux and…

Astrophysics · Physics 2009-11-11 Marina Battaglia , Paolo C. Grigis , Arnold O. Benz

In this work, we use HyLoop (Winter et al. 2011), a loop model that can incorporate the effects of both MHD and non-thermal particle populations, to simulate soft X-ray emissions in various situations. First of all, we test the effect of…

Solar and Stellar Astrophysics · Physics 2012-01-30 Katharine K. Reeves , Henry D. Winter , Natalie L. Larson

Context. We present an analysis of a GOES M1.8 flare with excellent observational coverage in UV, EUV, and X-ray, including observations from the instruments IRIS, SDO with AIA, Hinode/EIS, Hinode/XRT, and Solar Orbiter with the…

The origin of hard X-rays and gamma-rays emitted from the solar atmosphere during occulted solar flares is still debated. The hard X-ray emissions could come from flaring loop tops rising above the limb or Coronal Mass Ejections (CME) shock…

In the standard solar flare scenario, a large number of particles are accelerated in the corona. Nonthermal electrons emit both X-rays and radio waves. Thus, correlated signatures of the acceleration process are predicted at both…

Solar and Stellar Astrophysics · Physics 2015-05-13 Marina Battaglia , Arnold O. Benz

We present the relation of the spatial distribution of H-alpha kernels with the distribution of hard X-ray (HXR) sources seen during the 2001 April 10 solar flare. This flare was observed in H-alpha with the (Sartorius) telescope at Kwasan…

Poynting flux generated by random shuffling of photospheric magnetic footpoints is transferred through the upper atmosphere of the Sun where the plasma is heated to over 1 MK in the corona. High spatiotemporal resolution observations of the…

Solar and Stellar Astrophysics · Physics 2024-11-20 L. P. Chitta , M. van Noort , H. N. Smitha , E. R. Priest , L. H. M. Rouppe van der Voort

How and where are coronal loops rooted in the solar lower atmosphere? The details of the magnetic environment and its evolution at the footpoints of coronal loops are crucial to understanding the processes of mass and energy supply to the…