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This paper is the first of a series describing the results of the Australia Telescope Hubble Deep Field South (ATHDFS) radio survey. The survey was conducted at four wavelengths - 20, 11, 6, and 3 cm, over a 4-year period, and achieves an…

We report on new spectro-polarimetric measurements with simultaneous filter imaging observation, revealing the frequent appearance of polarization signals indicating high-speed, probably supersonic, downflows that are associated with at…

Sunspot penumbrae show high-velocity patches along the periphery. The high-velocity downflow patches are believed to be the return channels of the Evershed flow. We aim to investigate their structure in detail using Hinode SOT/SP…

Solar and Stellar Astrophysics · Physics 2015-06-16 Michiel van Noort , Andreas Lagg , Sanjiv Tiwari , Sami Solanki

Broad Absorption Line Quasars (BALQs) generally exhibit significant outflows that may interact with the surrounding medium, resulting in radio emission. We selected a sample of 13 powerful radio-quiet (RQ) BALQs, where the UV outflow…

Astrophysics of Galaxies · Physics 2026-01-22 Sina Chen , Ehud Behar , Ari Laor , Nahum Arav

A ubiquitous presence of weak energy releases is one of the most promising hypotheses to explain coronal heating, referred to as the nanoflare hypothesis. The accelerated electrons associated with such weak heating events are also expected…

Solar and Stellar Astrophysics · Physics 2022-10-12 Rohit Sharma , Divya Oberoi , Marina Battaglia , Sam Krucker

We report spectropolarimetric observations of a supersonic downflow impacting the lower atmosphere within a large sunspot umbra. This work is an extension of Schad et al. 2016 using observations acquired in the He I 10830 Angstrom triplet…

Solar and Stellar Astrophysics · Physics 2021-05-28 Thomas A. Schad , Gabriel I. Dima , Tetsu Anan

Ultraluminous supersoft sources (ULSs) are defined by a thermal spectrum with colour temperatures ~0.1 keV, bolometric luminosities ~ a few 10^39 erg/s, and almost no emission above 1 keV. It has never been clear how they fit into the…

High Energy Astrophysical Phenomena · Physics 2016-01-27 Ryan Urquhart , Roberto Soria

We present the X-ray analysis of coronal properties in a statistically representative sample of 23 mostly radio-quiet AGN from the SUBWAYS campaign (SUpermassive Black holes Winds in XrAYs), focusing on quasars at redshifts $0.1 < z < 0.4 $…

At low coronal temperatures around or below 1 MK distinct areas in the surroundings of active regions (AR) show emission at a level significantly below the emission coming from the quiet Sun (QS). These areas are referred to as dark halos,…

Solar and Stellar Astrophysics · Physics 2026-05-13 J. D. Nölke , S. K. Solanki , J. Hirzberger , H. Peter , L. P. Chitta , K. H. Glassmeier , D. Calchetti , G. Valori

The solar corona is orders of magnitude hotter than the underlying photosphere, but how the corona attains such high temperatures is still not understood. Soft X-ray (SXR) emission provides important diagnostics for thermal processes in the…

Solar and Stellar Astrophysics · Physics 2015-09-15 Amir Caspi , Thomas N. Woods , Harry P. Warren

Superflares on the solar type stars observed by \textit{Kepler} demonstrate the contrast in the optical continuum of the order 0.1--1 per cent. The mechanism of formation of this radiation is not firmly established. We consider a model…

Solar and Stellar Astrophysics · Physics 2020-04-09 B. A. Nizamov

Waves are thought to play a significant role in the heating of the solar atmosphere and the acceleration of the wind. Among the many types of waves observed in the Sun, the so-called p-modes with a 3 mHz frequency peak dominate the lower…

Dense plasma fragments were observed to fall back on the solar surface by the Solar Dynamics Observatory after an eruption on 7 June 2011, producing strong EUV brightenings. Previous studies investigated impacts in regions of weak magnetic…

Solar and Stellar Astrophysics · Physics 2016-11-15 A. Petralia , F. Reale , S. Orlando , P. Testa

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

Broad emission-line outflows of active galactic nuclei (AGNs) have been proposed for many years but are very difficult to quantitatively study because of the coexistence of the gravitationally-bound and outflow emission. We present detailed…

Astrophysics of Galaxies · Physics 2017-02-22 Shaohua Zhang , Hongyan Zhou , Xiheng Shi , Xiang Pan , Ji Wang , Ning Jiang , Tuo Ji , Peng Jiang , Wenjuan Liu , Huiyuan Wang

Metrewave solar type-III radio bursts offer a unique means to study the properties of turbulence across the coronal heights.Theoretical models have shown that the apparent intensity and size of the burst sources evolve at sub-second scales…

Solar and Stellar Astrophysics · Physics 2021-11-24 Atul Mohan

The GOES X1.5 class flare that occurred on August 30,2002 at 1327:30 UT is one of the few events detected so far at submillimeter wavelengths. We present a detailed analysis of this flare combining radio observations from 1.5 to 212 GHz (an…

Solar and Stellar Astrophysics · Physics 2015-05-13 C. G. Gimenez de Castro , G. Trottet , A. Silva-Valio , S. Krucker , J. E. R. Costa , P. Kaufmann , E. Correia , H. Levato

Although about 40% of the soft X-ray background emission in 0.4 to 1 keV range has extragalactic origins and thus is totally blocked by the Galactic absorption in midplane directions, it decreases at most by about 20 % in midplane. Suzaku…

Astrophysics · Physics 2008-10-14 K. Masui , K. Mitsuda , N. Y. Yamasaki , Y. Takei , S. Kimura , T. Yoshino , D. McCammon

With the purpose to investigate the radio emission of new ultracool objects, we carried out a targeted search in the recently discovered system VHS J125601.92$-$125723.9 (hereafter VHS 1256$-$1257); this system is composed by an equal-mass…

Solar and Stellar Astrophysics · Physics 2018-02-21 J. C. Guirado , R. Azulay , B. Gauza , M. A. Pérez-Torres , R. Rebolo , J. B. Climent , M. R. Zapatero-Osorio

The All-wavelength Extended Groth Strip International Survey (AEGIS) team presents broad-band spectral energy distributions (SEDs), from X-ray to radio wavelengths, for 71 galaxies spanning the redshift range 0.55-1.16 (<z>~0.7). Galaxies…

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