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Stellar atmosphere modelling predicts the luminosity and temperature of a star, together with parameters such as the effective gravity and the metallicity, by reproducing the observed spectral energy distribution. Most observational data…

Instrumentation and Methods for Astrophysics · Physics 2024-02-21 Iain McDonald , Albert A. Zijlstra , Nick L. J. Cox , Emma L. Alexander , Alexander Csukai , Ria Ramkumar , Alexander Hollings

Observational studies of magnetic fields are crucial. We introduce a process "ground state alignment" as a new way to determine the magnetic field direction in diffuse medium. The alignment is due to anisotropic radiation impinging on the…

Astrophysics of Galaxies · Physics 2013-02-15 Huirong Yan , A. Lazarian

Polarization induced by cosmological scalar perturbations leads to a typical anisotropy pattern, which can best be analyzed in Fourier domain. This allows one to unambiguously distinguish cosmological signal of polarization from other…

Astrophysics · Physics 2009-10-28 Uros Seljak

Artificial Intelligence algorithms are introduced in this work as a tool to predict the performance of new chemical compounds as alternative propellants for electric propulsion, focusing on predicting their ionisation characteristics and…

Instrumentation and Methods for Astrophysics · Physics 2025-10-01 Angel Pan Du , Miguel Arana-Catania , Enric Grustan Gutiérrez

We show that atomic alignment presents a reliable way to study topology of astrophysical magnetic fields. The effect of atomic alignment arises from modulation of the relative population of the sublevels of atomic ground state pumped by…

Astrophysics · Physics 2008-11-26 Huirong Yan , A. Lazarian

The charged environment within a dense plasma leads to the phenomenon of ionization potential depression (IPD) for ions embedded in the plasma. Accurate predictions of the IPD effect are of crucial importance for modeling atomic processes…

Plasma Physics · Physics 2014-07-10 Sang-Kil Son , Robert Thiele , Zoltan Jurek , Beata Ziaja , Robin Santra

XENON10 is an experiment designed to directly detect particle dark matter. It is a dual phase (liquid/gas) xenon time-projection chamber with 3D position imaging. Particle interactions generate a primary scintillation signal (S1) and…

Cosmic ray nuclei fluxes are expected to be measured with high precision in the near future. For instance, high quality data on the antiproton component could give important clues about the nature of the astronomical dark matter. A very…

Astrophysics · Physics 2008-11-26 D. Maurin , F. Donato , R. Taillet , P. Salati

A technique is presented for producing synthetic images from numerical simulations whereby the image resolution is adapted around prominent features. In so doing, adaptive image ray-tracing (AIR) improves the efficiency of a calculation by…

Instrumentation and Methods for Astrophysics · Physics 2015-05-20 E. R. Parkin

The atmospheres of planets (including Earth) and the outer layers of stars have often been treated in radiative transfer as plane-parallel media, instead of spherical shells, which can lead to inaccuracy, e.g. limb darkening. We give an…

Statistical Mechanics · Physics 2009-11-11 Michael J. Caola

This work describes a procedure to derive several fundamental parameters such as the effective temperature, surface gravity, equatorial rotational velocity and microturbulent velocity. In this work, we have written a numerical procedure in…

Solar and Stellar Astrophysics · Physics 2014-07-18 E. Aydi , M. Gebran , R. Monier , F. Royer , A. Lobel , R. Blomme

The gas that is present in the interstellar medium is usually very far removed from (local) thermodynamic equilibrium, and in some cases may also not be in a steady-state equilibrium with its surroundings. The physics of this material is…

Solar and Stellar Astrophysics · Physics 2020-02-17 P. A. M. van Hoof , G. C. Van de Steene , F. Guzmán , M. Dehghanian , M. Chatzikos , G. J. Ferland

The newly published spectra of protons and helium over time directly measured in space by the AMS-02 experiment for the period 2011--2017 provide a unique opportunity to calibrate ground-based neutron monitors (NMs). Here, calibration of…

Cosmic rays are usually assumed to be the main ionization agent for the interior of molecular clouds where UV and X-ray photons cannot penetrate. Here we test this hypothesis by limiting ourselves to the case of diffuse clouds and assuming…

High Energy Astrophysical Phenomena · Physics 2018-08-22 V. H. M. Phan , G. Morlino , S. Gabici

It has been known in potential theory that, for some kernels matrices corresponding to well-separated point sets, fast analytical low-rank approximation can be achieved via the use of proxy points. This proxy point method gives a…

Numerical Analysis · Mathematics 2019-03-22 Xin Ye , Jianlin Xia , Lexing Ying

A proper modelling of the cosmic-ray ionisation rate within gas clouds is crucial to describe their chemical evolution accurately. However, this modelling is computationally demanding because it requires the propagation of cosmic rays…

Astrophysics of Galaxies · Physics 2025-07-08 G. Latrille , A. Lupi , S. Bovino , T. Grassi , G. Sabatini , M. Padovani

(Abridged) The propagation of ionizing radiation through model atmospheres of terrestrial-like exoplanets is studied for a large range of column densities and incident photon energies using a Monte Carlo code we have developed to treat…

Astrophysics · Physics 2009-06-08 David S. Smith , John Scalo , J. Craig Wheeler

Cosmic ray protons propagating in a spatially-homogeneous but time-dependent field of axions or axion-like particles (ALPs) emit photons in a way that is reminiscent of Cherenkov radiation by charged particles in a preferred background. We…

High Energy Physics - Phenomenology · Physics 2011-08-18 H. Tam , Q. Yang

To simulate the interaction of cosmic rays with the Earth atmosphere requires highly complex computational resources and several statistical techniques have been developed to simplify those calculations. It is common to implement the…

Instrumentation and Methods for Astrophysics · Physics 2015-12-10 A. Estupiñán , H. Asorey , L. A. Núñez

The fluxes of light antinuclei A<=4 induced near earth by Cosmic Ray intera ctions with the interstellar matter in the Galaxy and with the Earth atmosphere, are calculated in a phenomenological framework. The hadronic production cross…

Astrophysics · Physics 2009-11-10 R. Duperray , B. Baret , D. Maurin , G. Boudoul , A. Barrau , L. Derome , K. Protasov , M. Buenerd