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The baryonic content and physical properties of the warm and hot ($10^5\lesssim T\lesssim 10^7$ K) phases of the circumgalactic medium (CGM) are poorly constrained, owing to the lack of observables probing the requisite range of…

Astrophysics of Galaxies · Physics 2018-08-08 Lluís Mas-Ribas , Joseph F. Hennawi

Coronal loops in active regions are the subjects of intensive investigation, but the important diffuse 'unresolved' emission in which they are embedded has received relatively little attention. Here we measure the densities and emission…

Solar and Stellar Astrophysics · Physics 2019-03-06 David H. Brooks

The surfaces of neutron stars are likely sources of strongly polarized soft X rays due to the presence of strong magnetic fields. Scattering transport in the surface layers is critical to the determination of the emergent anisotropy of…

High Energy Astrophysical Phenomena · Physics 2023-03-15 Kun Hu , Matthew G. Baring , Joseph A. Barchas , George Younes

A solar filament is a dense cool condensation that is supported and thermally insulated by magnetic fields in the rarefied hot corona. Its evolution and stability, leading to either an eruption or disappearance, depend on its coupling with…

Solar and Stellar Astrophysics · Physics 2019-07-04 L. P. Chitta , H. Peter , L. Li

We consider the polarization of 21cm line radiation from the epoch of reionization due to both intrinsically polarized emission and secondary mechanisms. We argue that Thomson scattering of the 21cm quadrupole by the reionized universe is…

Astrophysics · Physics 2009-11-11 Daniel Babich , Abraham Loeb

In the classical flare picture, hard X-ray emission from the chromosphere is succeeded by soft-X-ray emission from hot plasma in the flare loop, the soft X-ray emission being a direct consequence of the impact of the non-thermal particle…

Solar and Stellar Astrophysics · Physics 2015-05-13 M. Battaglia , L. Fletcher , A. O. Benz

Coronal density, temperature and heat flux distributions for the equatorial and polar corona have been deduced by Lemaire [2012] from Saito's model of averaged coronal white light (WL) brightness and polarization observations. They are…

Solar and Stellar Astrophysics · Physics 2015-06-05 V. Pierrard , K. Borremans , J. F. Lemaire

We developed an automated procedure for the identification of transient brightenings in images from the X-ray telescope on-board Hinode taken with an Al Poly filter in the equatorial coronal holes, polar coronal holes, and the quiet Sun…

Solar and Stellar Astrophysics · Physics 2015-05-18 S. Subramanian , M. S. Madjarska , J. G. Doyle

Recent observations from Parker Solar Probe have revealed that the solar wind has a highly variable structure. How this complex behaviour is formed in the solar corona is not yet known, since it requires omnipresent fluctuations, which…

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

We present spectropolarimetric imaging observations of the solar corona at low frequencies (80 - 240 MHz) using the Murchison Widefield Array (MWA). These images are the first of their kind, and we introduce an algorithm to mitigate an…

Solar and Stellar Astrophysics · Physics 2019-09-04 Patrick I. McCauley , Iver H. Cairns , Stephen M. White , Surajit Mondal , Emil Lenc , John Morgan , Divya Oberoi

We consider the polarization arising from scattering in an envelope illuminated by a central anisotropic source. Spherical harmonics are used to describe both the light source anisotropy and the envelope density distribution functions of…

Astrophysics · Physics 2008-12-16 R Ignace , M Al-Malki , J Simmons , J C Brown , D Clarke , J Carson

We conducted a high-resolution numerical simulation of the solar corona above a stable active region. The aim is to test the field-line braiding mechanism for a sufficient coronal energy input. We also check the applicability of scaling…

Solar and Stellar Astrophysics · Physics 2018-05-17 Philippe-A. Bourdin , Sven Bingert , Hardi Peter

We discuss features of coronal mass ejections (CMEs) that are specific to heliospheric observations at large elongation angles. Our analysis is focused on a series of two eruptions that occurred on 2007 January 24-25, which were tracked by…

Space Physics · Physics 2009-05-18 N. Lugaz , A. Vourlidas , I. I. Roussev , C. Jacobs , W. B. Manchester , O. Cohen

(Abridged abstract) We present an analysis of the X-ray emission of the rapidly rotating giant star YY Mensae observed by Chandra HETGS and XMM-Newton. Although no obvious flare was detected, the X-ray luminosity changed by a factor of two…

High sensitivity observations of Halpha polarization of 30 flares of different sizes and disk positions are reported. Both filter and spectrographic techniques have been used. The ZIMPOL system eliminates spurious polarizations due to…

Astrophysics · Physics 2009-11-10 M. Bianda , A. O. Benz , J. O. Stenflo , G. Kueveler , R. Ramelli

Massive star binaries are critical laboratories for measuring masses and stellar wind mass-loss rates. A major challenge is inferring viewing inclination and extracting information about the colliding wind interaction (CWI) region.…

Solar and Stellar Astrophysics · Physics 2022-07-06 Richard Ignace , Andrew Fullard , Manisha Shrestha , Yael Naze , Kenneth Gayley , Jennifer L Hoffman , Jamie R Lomax , Nicole St-Louis

We apply computational seismic holography to high-frequency helioseismic observations of the quiet Sun from SDO/HMI to locate predominant sources of seismic emission with respect to the structure of the solar granulation. The regions of…

Solar and Stellar Astrophysics · Physics 2013-07-05 Charles Lindsey , Alina Donea

We update the SOHO/SWAN H Lyman-alpha brightness analysis to cover the 1996-2008 time interval. A forward model applied to the intensity maps provides the latitude and time dependence of the interstellar Hydrogen ionisation rate over more…

Solar and Stellar Astrophysics · Physics 2010-03-23 Rosine Lallement , Eric Quemerais , Philippe Lamy , Jean-Loup Bertaux , Stephane Ferron , Walter Schmidt

A compact X-class flare on 2004-Feb-26 showed a concentrated source of hard X-rays at the tops of the flare's loops. This was analyzed in previous work (Longcope et al. 2010), and interpreted as plasma heated and compressed by slow…

Solar and Stellar Astrophysics · Physics 2016-12-28 Dana Longcope , Jiong Qiu , Jasmine Brewer