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A discrete tomography method has been developed that is able to reconstruct three-dimensional coronal mass ejection (CME) density structure. We test the method by producing synthetic coronagraph imagery for three events using the…

We present the first models allowing one to explore in a consistent way the influence of changes in the alpha-element-to-iron abundance ratio on the high-resolution spectral properties of evolving stellar populations. The models cover the…

Astrophysics · Physics 2008-01-08 P. Coelho , G. Bruzual , S. Charlot , A. Weiss , B. Barbuy , J. Ferguson

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

Electric currents play an important role in the energy balance of the plasma in the solar atmosphere. They are also indicative of non-potential magnetic fields and magnetic reconnection. Unfortunately, the direct measuring of electric…

Solar and Stellar Astrophysics · Physics 2023-01-25 J. M. Borrero , A. Pastor Yabar

The calculation of line widths constitutes theoretical and computational challenges in the calculation of opacities of hot dense plasmas. Opacity models use line broadening approximations that are untested at stellar interior conditions.…

Solar and Stellar Astrophysics · Physics 2016-06-22 M. Krief , A. Feigel , D. Gazit

Since the Lalpha rocket observations of (Gabriel, Solar Phys. 21, 392, 1971), it has been realized that the hydrogen (H) lines could be observed in the corona and offer an interesting diagnostic for the temperature, density, and radial…

Solar and Stellar Astrophysics · Physics 2016-11-15 Jean-Claude Vial , Martine Chane-Yook

We discuss the potential of high sensitivity mid-IR and far-IR spectroscopy to proof the physical properties of active nuclei and starburst regions of local and distant galaxies. For local galaxies, it will be possible to map the discs and…

Astrophysics · Physics 2007-05-23 Luigi Spinoglio , Anna Maria Di Giorgio , Paolo Saraceno

Nowadays, several opacity codes are able to provide data for stellar structure models, but the computed opacities may show significant differences. In this work, we present state-of-the-art precise spectral opacity calculations, illustrated…

Solar and Stellar Astrophysics · Physics 2019-04-30 Jean-Christophe Pain , Franck Gilleron , Maxime Comet

We present coordinated coronal observations of the August 21, 2017 total solar eclipse with the Airborne Infrared Spectrometer (AIR-Spec) and the Extreme-ultraviolet Imaging Spectrometer (EIS). These instruments provide an unprecedented…

Solar and Stellar Astrophysics · Physics 2019-08-07 Chad A. Madsen , Jenna E. Samra , Giulio Del Zanna , Edward E. DeLuca

Rescattering electrons offer great potential as probes of molecular properties on ultrafast timescales. The most famous example is molecular tomography, in which high harmonic spectra of oriented molecules are mapped to ``tomographic…

Atomic Physics · Physics 2016-09-28 Zachary B. Walters , Stefano Tonzani , Chris H. Greene

Characterizing prestellar cores in star-forming regions is an important step towards the validation of theoretical models of star formation. Thanks to their sub-arcsecond resolution, ALMA observations can potentially provide samples of…

Astrophysics of Galaxies · Physics 2023-05-05 Paolo Padoan , Veli-Matti Pelkonen , Mika Juvela , Troels Haugbølle , Åke Nordlund

This paper describes the development of X-ray diffractive optics for imaging solar flares with better than 0.1 arcsec angular resolution. X-ray images with this resolution of the \geq10 MK plasma in solar active regions and solar flares…

Instrumentation and Methods for Astrophysics · Physics 2015-06-05 B. R. Dennis , G. K. Skinner , M. J. Li , A. Y. Shih

Chromospheric modeling of observed differences in stellar activity lines is imperative to fully understand the upper atmospheres of late-type stars. We present one-dimensional parametrized chromosphere models computed with the atmosphere…

We use coronal imaging observations with SDO/AIA, and Hinode/EIS spectral data, to explore the potential of narrow band EUV imaging data for diagnosing the presence of hot (T >~5MK) coronal plasma in active regions. We analyze observations…

Solar and Stellar Astrophysics · Physics 2015-06-04 Paola Testa , Fabio Reale

The increased time- and length-scale of classical molecular dynamics simulations have led to raw data flows surpassing storage capacities, necessitating on-the-fly integration of structural analysis algorithms. As a result, algorithms must…

We summarize the theory of coronagraphic optics, and identify a dimensionless fine-tuning parameter, F, which we use to describe the Lyot stop size in the natural units of the coronagraphic optical train and the observing wavelength. We…

Astrophysics · Physics 2009-11-06 A. Sivaramakrishnan , C. D. Koresko , R. B. Makidon , T. Berkefeld , M. J. Kuchner

We have used realistic Comptonization models to fit high quality BeppoSAX data of 6 Seyfert galaxies. Our main effort was to adopt a Comptonization model taking into account the anisotropy of the soft photon field. The most important…

The paper reports the results of two-dimensional particle-in-cell simulations of proton beam acceleration at the interactions of a 130 fs laser pulse of intensity from the range of 10^21-10^23 W/cm^2, predicted for the Extreme Light…

Plasma Physics · Physics 2017-08-01 Jaroslaw Domanski , Jan Badziak , Slawomir Jablonski

Given the current limited knowledge of meteor plasma micro-physics and its interaction with the surrounding atmosphere and ionosphere, meteors are a highly interesting observational target for high-resolution wide-field astronomical…

Earth and Planetary Astrophysics · Physics 2018-01-10 Dino Bektešević , Dejan Vinković , Andrew Rasmussen , Željko Ivezić

The extreme ultraviolet portion of the solar spectrum contains a wealth of diagnostic tools for probing the lower solar atmosphere in response to an injection of energy, particularly during the impulsive phase of solar flares. These include…

Solar and Stellar Astrophysics · Physics 2015-09-16 Ryan O. Milligan