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We present the first observations of the Sun with the Allen Telescope Array (ATA). We used up to six frequencies, from 1.43 to 6 GHz, and baselines from 6 to 300 m. To our knowledge, these are the first simultaneous multifrequency full-Sun…

Solar and Stellar Astrophysics · Physics 2016-11-25 Pascal Saint-Hilaire , Gordon J. Hurford , Garrett Keating , Geoffrey C. Bower , Colby Gutierrez-Kraybill

The Sun is an active source of radio emission which is often associated with energetic phenomena such as solar flares and coronal mass ejections (CMEs). At low radio frequencies (<100 MHz), the Sun has not been imaged extensively because of…

Using four years of full-disk-integrated coronal differential emission measures calculated in Schonfeld et al. (2017), we investigate the relative contribution of bremsstrahlung and gyroresonance emission in observations of F$_{10.7}$, the…

Solar and Stellar Astrophysics · Physics 2019-10-30 S. J. Schonfeld , S. M. White , C. J. Henney , R. A. Hock-Mysliwiec , R. T. J. McAteer

The solar corona is much hotter than the photosphere and chromosphere, but the physical mechanism responsible for heating the coronal plasma remains unidentified yet. The thermal microwave emission, which is produced in strong magnetic…

Solar and Stellar Astrophysics · Physics 2025-08-27 Alexey A. Kuznetsov , Gregory D. Fleishman , Gelu M. Nita , Sergey A. Anfinogentov

We report observations of white-light ejecta in the low corona, for two X-class flares on the 2013 May 13, using data from the Helioseismic and Magnetic Imager (HMI) of the Solar Dynamics Observatory. At least two distinct kinds of sources…

We report on the detection (10 \sigma) of 917 events of long-period (3 to 16 hours) intensity pulsations in the 19.5 nm passband of the SOHO Extreme ultraviolet Imaging Telescope. The data set spans from January 1997 to July 2010, i.e the…

Solar and Stellar Astrophysics · Physics 2014-03-05 F. Auchère , K. Bocchialini , J. Solomon , E. Tison

We present a broadband map of polarized diffuse emission at 167-198 MHz developed from data from the Murchison Widefield Array (MWA). The map is designed to improve visibility simulation and precision calibration for 21 cm Epoch of…

Cosmology and Nongalactic Astrophysics · Physics 2021-11-17 Ruby Byrne , Miguel F. Morales , Bryna Hazelton , Ian Sullivan , Nichole Barry , Christene Lynch , Jack L. B. Line , Daniel C. Jacobs

The spectra of coronal mass ejections (CMEs) in the low corona play a crucial role in understanding their origins and physical mechanism, and enhancing space weather forecasting. However, capturing these spectra faces significant…

Solar and Stellar Astrophysics · Physics 2025-04-01 Lami Chan , Xianyong Bai , Hui Tian , Yufei Feng , Yu Xu , Tibor Török , Yuhang Gao , Tanmoy Samanta , Zheng Sun

We analyzed ground-based low frequency ($<$100\,MHz) radio spectral and imaging data of the solar corona obtained with the facilities in the Gauribidanur observatory during the same time as the very weak soft X-ray flares (sub A-class, flux…

Solar and Stellar Astrophysics · Physics 2021-09-20 R. Ramesh , C. Kathiravan , N. P. S. Mithun , S. V. Vadawale

Polarization behaviour shows a transition in the pulsar population, where energetic sources with higher spin-down energy loss, $\dot{E} > 10^{34}$ erg~s$^{-1}$, often have fractional linear polarisation ($L/I$) close to 100\%, while below…

High Energy Astrophysical Phenomena · Physics 2025-05-20 Dipanjan Mitra , Rahul Basu , George I. Melikidze

Quasi-periodic propagating intensity disturbances have been observed in large coronal loops in EUV images over a decade, and are widely accepted to be slow magnetosonic waves. However, spectroscopic observations from Hinode/EIS revealed…

Solar and Stellar Astrophysics · Physics 2015-11-04 X. Fang , D. Yuan , T. Van Doorsselaere , R. Keppens , C. Xia

We present a search for the synchrotron emission from the synchrotron cosmic web by cross correlating 180MHz radio images from the Murchison Widefield Array with tracers of large scale structure (LSS). We use two versions of the radio image…

Cosmology and Nongalactic Astrophysics · Physics 2017-04-12 Tessa Vernstrom , Bryan M. Gaensler , Shea Brown , Emil Lenc , Ray P. Norris

In this work we performed a polarimetric study of a fast and wide coronal mass ejection (CME) observed on 12 July 2012 by the COR1 and COR2 instruments onboard Solar TErrestrial RElations Observatory (STEREO) mission. The CME source region…

Solar and Stellar Astrophysics · Physics 2022-07-20 Marilena Mierla , Bernd Inhester , Andrei N. Zhukov , Sergei V. Shestov , Alessandro Bemporad , Philippe Lamy , Serge Koutchmy

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…

The observed solar activity is believed to be driven by the dissipation of nonpotential magnetic energy injected into the corona by dynamic processes in the photosphere. The enormous range of scales involved in the interaction makes it…

Solar and Stellar Astrophysics · Physics 2015-06-12 Vadim M. Uritsky , Joseph M. Davila , Leon Ofman , Aaron J. Coyner

Weak Impulsive Narrowband Quiet Sun Emissions (WINQSEs) are a newly discovered class of radio emission from the solar corona. These emissions are characterized by their extremely impulsive, narrowband and ubiquitous nature. We have…

Solar and Stellar Astrophysics · Physics 2023-08-09 Surajit Mondal , Divya Oberoi , Ayan Biswas , Devojyoti Kansabanik

It has been proposed that coherent radio emission could be emitted during or shortly following a gamma-ray burst (GRB). Here we present a low-frequency ($170-200$ MHz) search for radio pulses associated with long-duration GRBs using the…

Two coherent radio emission mechanisms operate in stellar coronae: plasma emission and cyclotron emission. They directly probe the electron density and magnetic field strength respectively. Most stellar radio detections have been made at…

Solar and Stellar Astrophysics · Physics 2020-11-11 H. K. Vedantham

We carried out polarimetric observations of the white-light corona during the total solar eclipses that occurred on 2017 August 21 and 2019 July 2, and successfully obtained data at two different sites for both eclipses. After eliminating…

Solar and Stellar Astrophysics · Physics 2021-11-17 Yoichiro Hanaoka , Yoshiaki Sakai , Koichi Takahashi

Magnetic loops filled with hot plasma are the main building blocks of the solar corona. Usually they have lengths of the order of the barometric scale height in the corona that is 50 Mm. Previously it has been suggested that miniature…

Solar and Stellar Astrophysics · Physics 2017-03-15 Krzysztof Barczynski , Hardi Peter , Sabrina L. Savage