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Recent SECCHI COR2 observations on board STEREO-A spacecraft have detected density structures at a distance of 2.5--15~R propagating with periodicity of about 90~minutes. The observations show that the density structures probably formed in…

Solar and Stellar Astrophysics · Physics 2017-04-26 O. S. Pylaev , T. V. Zaqarashvili , A. I. Brazhenko , V. N. Melnik , A. Hanslmeier , M. Panchenko

Recent observations revealed that the solar atmosphere is highly structured in density, temperature and magnetic field. The presence of these gradients may lead to the appearance of currents in the plasma, which in the weakly collisional…

Astrophysics · Physics 2009-11-13 R. Mecheri , E. Marsch

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

Increasing evidence for coronal heating contributions from cooler solar atmospheric layers, notably quiet Sun (QS) conditions, challenges standard solar atmospheric descriptions of bright transition region (TR) emission. As such, questions…

Solar and Stellar Astrophysics · Physics 2015-09-16 N. Brice Orange , David L. Chesny , Hakeem M. Oluseyi

We aim to investigate the temperature enhancements and formation heights of impulsive heating phenomena in solar active-regions such as Ellerman bombs (EBs), ultraviolet bursts (UVBs), and flaring active-region fibrils (FAFs) using…

Solar and Stellar Astrophysics · Physics 2020-11-04 J. M. da Silva Santos , J. de la Cruz Rodríguez , S. M. White , J. Leenaarts , G. J. M. Vissers , V. H. Hansteen

The \textit{Sun Watcher using Active Pixel system detector and Image Processing}(SWAP) on board the \textit{PRoject for OnBoard Autonomy\todash 2} (PROBA\todash 2) spacecraft provides images of the solar corona in EUV channel centered at…

Solar and Stellar Astrophysics · Physics 2012-06-11 K. Chandrashekhar , S. Krishna Prasad , D. Banerjee , B. Ravindra , Daniel B. Seaton

We analyze a set of three RXTE Target of Opportunity observations of the Galactic microquasar GRS 1915+105, observed on April 2000, during a multi-wavelength campaign. During the three observations, a strong, variable low frequency (2-9 Hz)…

Astrophysics · Physics 2009-11-07 J. Rodriguez , Ph. Durouchoux , I. F. Mirabel , Y. Ueda , M. Tagger , K. Yamaoka

Solar corona is much hotter than lower layers of the solar atmosphere-photosphere and chromosphere. The coronal temperature is up to 1MK in quiet sun areas, while up to several MK in active regions, which implies a key role of magnetic…

Solar and Stellar Astrophysics · Physics 2025-06-24 Gregory D. Fleishman , Alexey A. Kuznetsov , Gelu M. Nita

Recently, in a few case studies we demonstrated that gyrosynchrotron microwave emission can be detected directly from the acceleration region when the trapped electron component is insignificant. For the statistical study reported here, we…

Solar and Stellar Astrophysics · Physics 2016-07-27 Gregory D. Fleishman , Gelu M. Nita , Eduard P. Kontar , Dale E. Gary

We present first results of a solar radio event observed with the Owens Valley Radio Observatory Long Wavelength Array (OVRO-LWA) at metric wavelengths. We examine a complex event consisting of multiple radio sources/bursts associated with…

Solar and Stellar Astrophysics · Physics 2021-01-27 Sherry Chhabra , Dale E. Gary , Gregg Hallinan , Marin M. Anderson , Bin Chen , Lincoln J. Greenhill , Danny C. Price

The presence and interplay of continuous cooling and heating processes maintaining the corona of the Sun at the observed one million K temperature were recently understood to have crucial effects on the dynamics and stability of…

Solar and Stellar Astrophysics · Physics 2021-12-16 D. Y. Kolotkov , D. I. Zavershinskii , V. M. Nakariakov

At the beginning of the 4 November 2015 flare, in the 1300 -- 2000 MHz frequency range, we observed a very rare slowly positively drifting burst. We searched for associated phenomena in simultaneous EUV observations made by IRIS, SDO/AIA,…

Solar and Stellar Astrophysics · Physics 2018-04-18 Marian Karlicky , Alena Zemanova , Jaroslav Dudik , Krzysztof Radiszewski

Low-frequency radio phenomena are due to the presence of nonthermal electrons in the interplanetary (IP) medium. Understanding these phenomena is important in characterizing the space environment near Earth and other destinations in the…

Solar and Stellar Astrophysics · Physics 2016-05-10 Nat Gopalswamy

Type-C quasi-periodic oscillations (QPOs) in black hole X-ray transients can appear when the source is in the low-hard and hard-intermediate states. The spectral-timing evolution of the type-C QPO in MAXI J1535-571 has been recently studied…

In X-ray observations of hard state black hole X-ray binaries, rapid variations in accretion disc and coronal power-law emission are correlated and show Fourier-frequency-dependent time lags. On short (~0.1 s) time-scales, these lags are…

We search for indications of waves in the 25-2000 MHz radio spectrum of the 1 August 2010 event (SOL2010-08-01T08:57:00L075C013), where fast propagating waves in the solar corona with the periods of 181, 69, and 40 seconds were detected in…

Solar and Stellar Astrophysics · Physics 2016-12-14 M. Karlicky , J. Rybak

A kilohertz quasi-periodic oscillation (kHz QPO) is an observationally robust high-frequency timing feature detected from neutron star low-mass X-ray binaries (LMXBs). This feature can be very useful to probe the superdense core matter of…

High Energy Astrophysical Phenomena · Physics 2012-09-18 Arunava Mukherjee , Sudip Bhattacharyya

Microflares have been considered to be among the major energy input sources to form active solar corona. To investigate the response of the low atmosphere to events, we conducted an ALMA observation at 3 mm coordinated with IRIS and Hinode…

Solar and Stellar Astrophysics · Physics 2021-12-08 Toshifumi Shimizu , Masumi Shimojo , Masashi Abe

We present coronal density profiles derived from low-frequency (80-240 MHz) imaging of three type III solar radio bursts observed at the limb by the Murchison Widefield Array (MWA). Each event is associated with a white light streamer at…

Solar and Stellar Astrophysics · Physics 2018-10-17 Patrick I. McCauley , Iver H. Cairns , John Morgan

Coherent low-frequency ($\lesssim 200$ MHz) radio emission from stars encodes the conditions of the outer corona, mass-ejection events, and space weather. Previous low-frequency searches for radio emitting stellar systems have lacked the…