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We present radio and X-ray observations of an impulsive solar flare that was moderately intense in microwaves, yet showed very meager EUV and X-ray emission. The flare occurred on 2001 Oct 24 and was well-observed at radio wavelengths by…

Astrophysics · Physics 2009-06-23 T. S. Bastian , G. D. Fleishman , D. E. Gary

We study a solar flare that occurred on September 10, 2002, in active region NOAA 10105 starting around 14:52 UT and lasting approximately 5 minutes in the radio range. The event was classified as M2.9 in X-rays and 1N in H\alpha. Solar…

Solar and Stellar Astrophysics · Physics 2015-06-11 C. G. Giménez de Castro , G. D. Cristiani , P. J. A. Simões , C. H. Mandrini , E. Correia , P. Kaufmann

The relative amount of high temperature plasma has been found to be a useful diagnostic to determine the frequency of coronal heating on sub-resolution structures. When the loops are infrequently heated, a broad emission measure (EM) over a…

We have analyzed high-resolution X-ray spectra of a sample of 22 active stars observed with the High Energy Transmission Grating Spectrometer on {\em Chandra} in order to investigate their coronal plasma density. Densities where…

Astrophysics · Physics 2009-11-10 Paola Testa , Jeremy J. Drake , Giovanni Peres

In order to better understand the possibility of coronal heating by MHD waves, we analyze Fe xii 195.12{\AA} data observed with EUV Imaging Spectrometer (EIS) onboard Hinode. We performed a Fourier analysis of EUV intensity and Doppler…

Solar and Stellar Astrophysics · Physics 2015-05-19 Naomasa Kitagawa , Takaaki Yokoyama , Shinsuke Imada , Hirohisa Hara

With the observations from the Atmospheric Imaging Assembly and the Helioseismic and Magnetic Imager aboard the \emph{Solar Dynamics Observatory}, we statistically investigate the emerging dimmings (EDs) of 24 isolated active regions (IARs)…

Solar and Stellar Astrophysics · Physics 2015-06-11 Jun Zhang , Shuhong Yang , Yang Liu , Xudong Sun

Observations of radio noise storms can act as sensitive probes of nonthermal electrons produced in small acceleration events in the solar corona. We use data from noise storm episodes observed jointly by the Giant Metrewave Radio Telescope…

Solar and Stellar Astrophysics · Physics 2018-05-22 Tomin James , Prasad Subramanian

The heating of ions and electrons due to turbulent dissipation plays a crucial role in the thermodynamics of the solar wind and other plasma environments. Using magnetic field and thermal plasma observations from the first two perihelia of…

Solar and Stellar Astrophysics · Physics 2023-04-12 Niranjana Shankarappa , Kristopher G. Klein , Mihailo M Martinović

Data obtained in the framework of the INTERBALL-Tail Probe (1995-2000) and RHESSI (from 2002 to the present) projects have revealed variations in the X-ray intensity of the solar corona in the photon energy range of 2-15 keV during the…

High Energy Astrophysical Phenomena · Physics 2019-04-08 I. K. Mirzoeva , S. G. Chefranov

The moss is the area at the footpoint of the hot (3 to 5 MK) loops forming the core of the active region where emission is believed to result from the heat flux conducted down to the transition region from the hot loops. Studying the…

Solar and Stellar Astrophysics · Physics 2012-11-26 Neda Dadashi , Luca Teriaca , Durgesh Tripathi , Sami K. Solanki , Thomas Wiegelmann

We present a detailed analysis of a reflecting intensity perturbation in a large coronal loop that appeared as sloshing oscillation and lasted for at least one and a half periods. The perturbation is initiated by a microflare at one…

Solar and Stellar Astrophysics · Physics 2022-09-14 Fanxiaoyu Xia , Tongjiang Wang , Yang Su , Jie Zhao , Qingmin Zhang , Astrid M. Veronig , Weiqun Gan

In this paper, we present the results of an analysis of 481 weak solar flares, from A0.01 to the B \textit{GOES} class, that were observed during the period of extremely low solar activity from 2009 April to July. For all flares we measured…

Solar and Stellar Astrophysics · Physics 2017-06-20 A. S. Kirichenko , S. A. Bogachev

In the solar corona, magnetic reconnection occurs due to the finite resistivity of the plasma. At the same time, resistivity leads to ohmic heating. Therefore, the reconnecting current sheet should heat the surrounding plasma. This paper…

Solar and Stellar Astrophysics · Physics 2023-06-06 Anton Reva , Sergey Bogachev , Ivan Loboda , Artem Ulyanov , Alexey Kirichenko

A large sample of active-region-targeted time-series images from the Solar Dynamics Observatory / Atmospheric Imaging Assembly, the AIA Active Region Patch database ("AARPs", Paper I: Dissauer et al 2022) is used to investigate whether…

Solar and Stellar Astrophysics · Physics 2023-01-25 KD Leka , Karin Dissauer , Graham Barnes , Eric L. Wagner

We investigate the thermal properties of a solar flare by the observations of soft X-ray Telescope (XRT) on board Hinode and the Atmospheric Image Assembly on board the Solar Dynamics Observatory (SDO/AIA). Our analysis reveals a tenuous…

Solar and Stellar Astrophysics · Physics 2025-10-22 Xiaoyan Xie , Anna Chen , Crisel Suarez , Katharine K. Reeves , Soumya Roy , Christopher S. Moore , Nishu Karna , Joy Velasquez

Three dimensional electron density distributions in the solar corona are reconstructed for 100 Carrington Rotations (CR 2054$-$2153) during 2007/03$-$2014/08 using the spherically symmetric method from polarized white-light observations…

Solar and Stellar Astrophysics · Physics 2017-07-25 Tongjiang Wang , Nelson L. Reginald , Joseph M. Davila , O. Chris St. Cyr , William T. Thompson

We report on the variability of rotation periods of solar coronal layers with respect to temperature (or, height). For this purpose, we have used the observations from Atmospheric Imaging Assembly (AIA) telescope on board Solar Dynamics…

Solar and Stellar Astrophysics · Physics 2020-02-19 Jaidev Sharma , Brajesh Kumar , Anil K. Malik , Hari Om Vats

The Airborne Infrared Spectrometer (AIR-Spec) offers an unprecedented opportunity to explore the Near Infra-Red (NIR) wavelength range. It has been flown at two total solar eclipses, in 2017 and 2019. The wavelength range of the much…

Solar and Stellar Astrophysics · Physics 2023-03-01 G. Del Zanna , J. Samra , A. Monaghan , C. Madsen , P. Bryans , E. DeLuca , H. Mason , B. Berkey , A. de Wijn , Y. Rivera

Recent imaging observations of EUV line emissions have shown evidence for frequent flare-like events in a majority of the pixels in quiet regions of the solar corona. The changes in coronal emission measure indicate impulsive heating of new…

Astrophysics · Physics 2009-11-07 Arnold O. Benz , Sam Krucker

The aim of this work is to determine the multi-thermal characteristics and plasma energetics of an eruptive plasmoid and occulted flare observed by Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA). We study an event from…

Solar and Stellar Astrophysics · Physics 2015-06-12 I. G. Hannah , E. P. Kontar