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Within the quiet Sun corona imaged at 1 MK, much of the field of view consists of diffuse emission that appears to lack the spatial structuring that is so evident in coronal loops or bright points. We seek to determine if these diffuse…

It is extremely difficult to simulate the details of coronal heating and also make meaningful predictions of the emitted radiation. Thus, testing realistic models with observations is a major challenge. Observational signatures of coronal…

Solar and Stellar Astrophysics · Physics 2022-11-02 James A. Klimchuk , Kalman J. Knizhnik , Vadim M. Uritsky

We present some new accurate CCD photometry analysis of the white light solar corona at the time of the last 20 March 2015 total eclipse (airborne observations on a Falcon 7X and at ground-based Svalbard). We measured coronal brightness…

Solar and Stellar Astrophysics · Physics 2015-10-23 C. Bazin , J. Vilinga , R. Wittich , S. Koutchmy , J. Mouette , C. Nitschelm

Dating back to the first observations of the on-disk corona, there has been a qualitative link between the photosphere's magnetic network and enhanced transition-temperature plasma emission. These observations led to the development of a…

Solar and Stellar Astrophysics · Physics 2016-11-15 Donald Schmit , Bart De Pontieu

Recent high-resolution solar observations have unveiled the presence of small-scale loop-like structures in the lower solar atmosphere, often referred to as unresolved fine structures, low-lying loops, and miniature hot loops. These…

Solar and Stellar Astrophysics · Physics 2025-03-14 Annu Bura , Tanmoy Samanta , Alphonse Sterling , Yajie Chen , Jayant Joshi , Vasyl Yurchyshyn , Ronald L. Moore

We report high-resolution observations at mid-infrared wavelengths of a minor solar flare, SOL2014-09-24T17T17:50 (C7.0), using Quantum Well Infrared Photodetector (QWIP) cameras at an auxiliary of the McMath-Pierce telescope. The flare…

Solar and Stellar Astrophysics · Physics 2016-03-23 M Penn , S Krucker , H Hudson , M Jhabvala , D Jennings , A Lunsford , P Kaufmann

The central galaxies of some clusters can be strong emitters in the Ly$\alpha$ and H$\alpha$ lines. This emission may arise either from the cool/warm gas located in the cool core of the cluster or from the bright AGN within the central…

Cosmology and Nongalactic Astrophysics · Physics 2014-05-13 S. Khedekar , E. Churazov , S. Sazonov , R. Sunyaev , E. Emsellem

X-ray and EUV observations are an important diagnostic of various plasma parameters of the solar atmosphere during solar flares. Soft X-ray and EUV observations often show coronal sources near the top of flaring loops, while hard X-ray…

Solar and Stellar Astrophysics · Physics 2015-06-11 Marina Battaglia , Eduard P. Kontar

Thomson scattering of intense laser pulses from relativistic electrons allows us to generate high-brightness and tunable-polarization X/{\gamma}-ray pulses. This paper demonstrates the polarization control of the Thomson scattering source…

Accelerator Physics · Physics 2017-11-22 Hongze Zhang , Yingchao Du , Chuanxiang Tang , Lixin Yan , Wenhui Huang

Efficient radiation at second and/or higher harmonics of Wce has been suggested to circumvent the escaping difficulty of the electron cyclotron maser emission mechanism when it is applied to solar radio bursts, such as spikes. In our…

Solar and Stellar Astrophysics · Physics 2022-09-15 Mehdi Yousefzadeh , Yao Chen , Hao Ning , Mahboub Hosseinpour

We report for the first time the detection of thermal free-free emission from post-flare loops at 34GHz in images from the Nobeyama Radioheliograph (NoRH). We studied 8 loops, 7 of which were from regions with extremely strong coronal…

Solar and Stellar Astrophysics · Physics 2024-06-24 Costas E. Alissandrakis , Gregory D. Fleishman , Viktor V. Fedenev , Stephen M. White , Alexander T. Altyntsev

There is a thin transition region (TR) in the solar atmosphere where the temperature rises from 10,000 K in the chromosphere to millions of degrees in the corona. Little is known about the mechanisms that dominate this enigmatic region…

Flare loops form an integral part of eruptive events, being detected in the range of temperatures from X-rays down to cool chromospheric-like plasmas. While the hot loops are routinely observed by the Solar Dynamics Observatory's…

Solar and Stellar Astrophysics · Physics 2020-01-08 Július Koza , David Kuridze , Petr Heinzel , Sonja Jejčič , Huw Morgan , Maciej Zapiór

Prominences in the solar corona are hundredfold cooler and denser than their surroundings, with a total mass of 1.e13 up to 1.e15 g. Here we report on the first comprehensive simulations of three-dimensional, thermally and gravitationally…

Solar and Stellar Astrophysics · Physics 2015-06-22 Chun Xia , Rony Keppens , Patrick Antolin , Oliver Porth

Coronal loops, seen in solar coronal images, are believed to represent emission from magnetic flux tubes with compact cross-sections. We examine the 3D structure of plasma above an active region in a radiative magnetohydrodynamic simulation…

Solar and Stellar Astrophysics · Physics 2022-03-09 A. Malanushenko , M. C. M. Cheung , C. E. DeForest , J. A. Klimchuk , M. Rempel

We perform X-ray spectral and timing analyses of solar-like (spectral types F5--K8) and intermediate-type (B4--F4) Pleiads observed in a 40-ks XMM-Newton EPIC exposure. All 8 solar-like members have ``quasi-steady'' \lx $\ga 10^{29}$ erg/s…

Astrophysics · Physics 2009-11-10 K. R. Briggs , J. P. Pye

We examine spectropolarimetric data from the CoMP instrument, acquired during the evolution of the September 10th 2017 X8.2 solar flare on the western solar limb. CoMP captured linearly polarized light from two emission lines of Fe XIII at…

Solar and Stellar Astrophysics · Physics 2019-12-25 Ryan J. French , Philip G. Judge , Sarah A. Matthews , Lidia van Driel-Gesztelyi

The white-light continuum emissions in solar flares (i.e., white-light flares) are usually observed on the solar disk but, in a few cases, off the limb. Here we present on-disk as well as off-limb continuum emissions at 3600 {\AA} (in the…

Solar and Stellar Astrophysics · Physics 2024-02-13 Ying Li , Zhichen Jing , De-Chao Song , Qiao Li , Jun Tian , Xiaofeng Liu , Ya Wang , M. D. Ding , Andrea Francesco Battaglia , Li Feng , Hui Li , Weiqun Gan

We present the first optical polarimetric observations of the runaway microquasar LS 5039. Our results reveal the presence of a large amount (~5%) of polarized emission towards this binary system. By combining polarimetric and spectroscopic…

Astrophysics · Physics 2007-05-23 J. A. Combi , S. A. Cellone , J. Marti , M. Ribo , I. F. Mirabel , J. Casares

We analyse observations of the X9.3 solar flare (SOL2017-09-06T11:53) observed by SDO/HMI and Hinode/SOT. Our aim is to learn about the nature of the HMI pseudocontinuum Ic used as a proxy for the white-light continuum. From model…

Solar and Stellar Astrophysics · Physics 2018-07-04 M. Svanda , Jan Jurcak , Jana Kasparova , Lucia Kleint