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Context. Late O-type stars at luminosities $\log L/L_\odot \lesssim 5.2$ show weak winds with mass-loss rates lower than 10$^{-8} M_\odot$ yr$^{-1}$. This implies that their photospheric layers are not strongly affected by the stellar wind.…

Solar and Stellar Astrophysics · Physics 2023-03-08 Patrick Aschenbrenner , Norbert Przybilla , Keith Butler

We present the non-local thermodynamic equilibrium (non-LTE) calculations for O I with the updated model atom that includes quantum-mechanical rate coefficients for O I + H I inelastic collisions from the recent study of Barklem (2018). The…

Solar and Stellar Astrophysics · Physics 2018-08-23 Tatyana Sitnova , Lyudmila Mashonkina

Neutral hydrogen (HI) intensity mapping is a promising technique to probe the large-scale structure of the Universe, improving our understanding on the late-time accelerated expansion. In this work, we first scrutinize how an alternative…

Cosmology and Nongalactic Astrophysics · Physics 2022-01-12 Linfeng Xiao , Andre A. Costa , Bin Wang

The potential for laser-produced plasmas to yield fundamental insights into high energy density physics (HEDP) and deliver other useful applications can sometimes be frustrated by uncertainties in modeling the properties and behavior of…

Plasma Physics · Physics 2022-04-19 Chris Orban , Milad Fatenejad , Don Q. Lamb

We have simulated the formation of a galaxy cluster in a $\Lambda$CDM universe using twelve different codes modeling only gravity and non-radiative hydrodynamics (\art, \arepo, \hydra\ and 9 incarnations of GADGET). This range of codes…

The copper abundances of 29 metal-poor stars are determined based on the high resolution, high signal-to-noise ratio spectra from the UVES spectragraph at the ESO VLT telescope. Our sample consists of the stars of the Galactic halo, thick-…

Solar and Stellar Astrophysics · Physics 2018-08-08 J. R. Shi , H. L. Yan , Z. M. Zhou , G. Zhao

The THERMOS toolkit has been developed to calculate radiative properties of plasmas. This article contains a brief survey of some of its key features used by calculation of opacities and emissivities and by analysis of specific experiments.…

Plasma Physics · Physics 2019-10-23 I. Yu. Vichev , A. D. Solomyannaya , A. S. Grushin , D. A. Kim

The interpretation of observed spectra of stars in terms of fundamental stellar properties is a key problem in astrophysics. For FGK-type stars, the radiative transfer models are often computed using the assumption of local thermodynamic…

Solar and Stellar Astrophysics · Physics 2023-06-14 Maria Bergemann , Thomas Nordlander

Neutral sodium is a minority species in the atmospheres of late-type stars, and line formation in local thermodynamic equilibrium (LTE) is often a poor assumption, in particular for strong lines. We present an extensive grid of non-LTE…

Solar and Stellar Astrophysics · Physics 2015-05-27 K. Lind , M. Asplund , P. S. Barklem , A. K. Belyaev

We present results from luminosity, energy and polarization studies at a future Linear Collider. We compare e+e- and e-e- modes of operation and consider both NLC and TESLA beam parameter specifications at a center-of-mass energy of 500…

Accelerator Physics · Physics 2009-11-10 M. Woods , A. Florimonte , K. C. Moffeit , T. O. Raubenheimer , A. Seryi , C. Sramek

Non-local Thermodynamic Equilibrium (NLTE) calculations of hot white dwarf (WD) model atmospheres are the cornerstone of modern flux calibrations for the Hubble Space Telescope (HST) and for the CALSPEC database. These theoretical spectral…

Solar and Stellar Astrophysics · Physics 2020-06-17 Ralph Bohlin , Ivan Hubeny , Thomas Rauch

This manuscript presents verification cases that are developed to study the electrothermal instability (ETI). Specific verification cases are included to ensure that the unit physics components necessary to model the ETI are accurate,…

Plasma Physics · Physics 2021-03-10 R. L. Masti , C. L. Ellison , J. R. King , P. H. Stoltz , B. Srinivasan

In hot dense plasmas of intermediate or high-Z elements in the state of local thermodynamic equilibrium, the number of electronic configurations contributing to key macroscopic quantities such as the spectral opacity and equation of state,…

Plasma Physics · Physics 2021-03-31 Menahem Krief

Understanding the dynamics of the solar chromosphere is crucial to understanding energy transport across the solar atmosphere. The chromosphere is optically thick at many wavelengths and described by non-local thermodynamic equilibrium…

Solar and Stellar Astrophysics · Physics 2019-01-30 Jeffrey W. Reep , Stephen J. Bradshaw , Nicholas A. Crump , Harry P. Warren

As one of the most important elements in astronomy, iron abundance determinations need to be as accurate as possible. We investigate the accuracy of spectroscopic iron abundance analyses using archetypal metal-poor stars. We perform…

Solar and Stellar Astrophysics · Physics 2016-09-15 A. M. Amarsi , K. Lind , M. Asplund , P. S. Barklem , R. Collet

We investigated the reliability of our silicon atomic model and the influence of non-local thermodynamical equilibrium (NLTE) on the formation of neutral silicon (Si I) lines in the near-infrared (near-IR) H-band. We derived the…

Solar and Stellar Astrophysics · Physics 2016-10-20 Junbo Zhang , Jianrong Shi , Kaike Pan , Carlos Allende Prieto , Chao Liu

Given the current transformative potential of research that sits at the intersection of Deep Learning (DL) and Software Engineering (SE), an NSF-sponsored community workshop was conducted in co-location with the 34th IEEE/ACM International…

Radiative transfer simulations are now at the forefront of numerical astrophysics. They are becoming crucial for an increasing number of astrophysical and cosmological problems; at the same time their computational cost has come to the…

Understanding the behavior of the matter power spectrum on non-linear scales beyond the $\Lambda$CDM model is crucial for accurately predicting the large-scale structure (LSS) of the Universe in non-standard cosmologies. In this work, we…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-31 Emanuelly Silva , Ubaldo Zúñiga-Bolaño , Rafael C. Nunes , Eleonora Di Valentino

We perform the non-local thermodynamic equilibrium (NLTE) calculations for Ca I-II with the updated model atom that includes new quantum-mechanical rate coefficients for Ca I + H I collisions from two recent studies, that is, by Barklem and…

Solar and Stellar Astrophysics · Physics 2017-09-13 L. Mashonkina , T. Sitnova , A. K. Belyaev