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We used high-resolution observations from the New Vacuum Solar Telescope and the Solar Dynamics Observatory to carry out a detailed multiwavelength analysis of the fine structures in the flare ribbon of a C3.9-class flare on 22 April 2021.…

Solar and Stellar Astrophysics · Physics 2026-03-25 Tianyuan Chen , Xiaoli Yan , Zhike Xue , Jincheng Wang , Zhe Xu , Liheng Yang , Yadan Duan , Yian Zhou , Zongyin Wu , Qifan Dong , Guotang Wu , Xinsheng Zhang

The small-scale moving intensity enhancements remotely observed in the extreme ultraviolet images of the solar active regions, which we refer to as active region moving campfires (ARMCs), are related to local plasma temperature and/or…

Solar and Stellar Astrophysics · Physics 2022-06-08 B. M. Shergelashvili , E. Philishvili , S. Buitendag , S. Poedts , M. Khodachenko

The braiding of the solar coronal magnetic field via photospheric motions - with subsequent relaxation and magnetic reconnection -- is one of the most widely debated ideas of solar physics. We readdress the theory in the light of…

Astrophysics · Physics 2011-02-11 A. L. Wilmot-Smith , G. Hornig , D. I. Pontin

Using the Hilbert-Huang transform technique, we investigate the midrange periodicities in solar radio flux at 2800 MHz (F10.7) and sunspot areas (SAs) from February 1, 1947 to September 30, 2016. The following prominent results are found:…

Solar and Stellar Astrophysics · Physics 2018-11-21 Ying Mei , Hui Deng , Feng Wang

We report a quasi-periodic pulsation (QPP) event simultaneously detected from the spatial displacements of coronal loop at both EUV images and microwave emission during the preflare phase of a C1.1 flare on 2016 March 23. Using the motion…

Solar and Stellar Astrophysics · Physics 2020-04-22 Dong Li , Ying Li , Lei Lu , Qingmin Zhang , Zongjun Ning , Sergey Anfinogentov

In this study we combine the multiwavelength ultraviolet -- optical (Solar Dynamics Observatory, SDO) and radio (Nobeyama Radioheliograph, NoRH) observations to get further insight into space-frequency distribution of oscillations at…

Solar and Stellar Astrophysics · Physics 2015-05-13 D. Y. Kolobov , N. I. Kobanov , A. A. Chelpanov , A. A. Kochanov , S. A. Anfinogentov , S. A. Chupin , I. I. Myshyakov , V. E. Tomin

Decimetric radio observations of the impulsive solar flare on October 5, 1992, 09:25 UT show a long series of quasi-periodic pulsations deeply modulating a continuum in the 0.6-2 GHz range that is slowly drifting toward lower frequencies.…

Astrophysics · Physics 2007-05-23 B. Kliem , M. Karlicky , A. O. Benz

Longitudinal intensity oscillations along coronal loops that are interpreted as signatures of magneto-acoustic waves are observed frequently in different coronal structures. The aim of this paper is to estimate the physical parameters of…

Solar and Stellar Astrophysics · Physics 2016-04-13 A. Abedini

Some of local sources of the slow solar wind can be associated with spectroscopically detected plasma outflows at edges of active regions accompanied with specific signatures in the inner corona. The EUV telescopes (e.g. SPIRIT/CORONAS-F,…

Solar and Stellar Astrophysics · Physics 2012-05-03 V. Slemzin , L. Harra , A. Urnov , S. Kuzin , F. Goryaev , D. Berghmans

Magnetic reconnection is a rapid energy release process that is believed to be responsible for flares on the Sun and stars. Nevertheless, such flare-related reconnection is mostly detected to occur in the corona, while there have been few…

Solar and Stellar Astrophysics · Physics 2016-03-21 Jie Hong , M. D. Ding , Ying Li , Kai Yang , Xin Cheng , Feng Chen , Cheng Fang , Wenda Cao

Coronal mass ejections (CMEs) erupt and expand in a magnetically structured solar corona. Various indirect observational pieces of evidence have shown that the magnetic field of CMEs reconnects with surrounding magnetic fields, forming,…

The sunspot-associated sources at the frequency of 17 GHz give information on plasma parameters in the regions of magnetic field about B=2000 G at the level of the chromosphere-corona transition region. The observations of short period…

Solar and Stellar Astrophysics · Physics 2015-03-19 Vladimir E. Abramov-Maximov , George B. Gelfreikh , Kiyoto Shibasaki

Solar flare ribbons provide an important clue to the magnetic reconnection process and associated magnetic field topology in the solar corona. We detected a large-scale secondary flare ribbon of a circular shape that developed in…

Solar and Stellar Astrophysics · Physics 2017-12-13 Eun-Kyung Lim , Vasyl Yurchyshyn , Pankaj Kumar , Kyuhyoun Cho , Chaowei Jiang , Sujin Kim , Heesu Yang , Jongchul Chae , Kyung-Suk Cho , Jeongwoo Lee

Magnetic reconnection in the solar corona is thought to be unstable to the formation of multiple interacting plasmoids, and previous studies have shown that plasmoid dynamics can trigger MHD waves of different modes propagating outward from…

Solar and Stellar Astrophysics · Physics 2018-10-25 Elena Provornikova , J. Martin Laming , Vyacheslav S. Lukin

Evolution of a coronal loop in response to an impulsive energy release is numerically modelled. It is shown that the loop density evolution curves exhibit quasi-periodic perturbations with the periods given approximately by the ratio of the…

Astrophysics · Physics 2009-11-10 V. M. Nakariakov , D. Tsiklauri , A. Kelly , T. D. Arber , M. J. Aschwanden

Aims. To study intensity oscillations in the solar chromosphere/corona above a quiet-Sun magnetic network. Methods. We analyse the time series of He II 256.32, Fe XI 188.23 and Fe XII 195.12 spectral lines observed by EUV Imaging…

Astrophysics · Physics 2009-11-13 A. K. Srivastava , D. Kuridze , T. V. Zaqarashvili , B. N. Dwivedi

Magnetic reconnection occurs when new flux emerges into the corona and becomes incorporated into the existing coronal field. A new active region (AR) emerging in the vicinity of an existing AR provides a convenient laboratory in which…

Solar and Stellar Astrophysics · Physics 2020-01-08 Marika I. McCarthy , Dana W. Longcope , Anna Malanushenko , David E. McKenzie

Magnetic reconnection in the partially ionized solar chromosphere is studied in 2.5-dimensional magnetohydrodynamic simulations including radiative cooling and ambipolar diffusion. A Harris current sheet with and without a guide field is…

Solar and Stellar Astrophysics · Physics 2015-09-24 Lei Ni , Bernhard Kliem , Jun Lin , Ning Wu

Meridional circulation regulates the Sun's interior dynamics and magnetism. While it is well accepted that meridional flows are poleward at the Sun's surface, helioseismic observations have yet to provide a definitive answer for the depth…

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