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Over the last decade {\it ab initio} modeling of material properties has become widespread in diverse fields of research. It has proved to be a powerful tool for predicting various properties of matter under extreme conditions. We apply…

Solar and Stellar Astrophysics · Physics 2015-05-20 Piotr M. Kowalski , Mukremin Kilic

We compute model atmospheres and emergent spectra for low field (B<10^10 G) neutron stars, using new opacity and equation of state data from the OPAL project. These computations, incorporating improved treatments of flux transport and…

Astrophysics · Physics 2009-10-28 Mohan Rajagopal , Roger Romani

We describe advances on a method designed to derive accurate parameters of M dwarfs. Our analysis consists in comparing high-resolution infrared spectra acquired with the near-infrared spectro-polarimeter SPIRou to synthetic spectra…

Solar and Stellar Astrophysics · Physics 2022-09-28 P. I. Cristofari , J. -F. Donati , T. Masseron , P. Fouqué , C. Moutou , A. Carmona , E. Artigau , E. Martioli , G. Hébrard , E. Gaidos , X. Delfosse

We present a computationally efficient 1-D seasonal radiative model, with convective adjustment, of Jupiter's atmosphere. Our model takes into account radiative forcings from the main hydrocarbons (methane, ethane, acetylene), ammonia,…

Earth and Planetary Astrophysics · Physics 2020-11-13 Sandrine Guerlet , Aymeric Spiga , Thierry Fouchet , Hugues Delattre

High-resolution images of the solar surface show a granulation pattern of hot rising and cooler downward-sinking material -- the top of the deep-reaching solar convection zone. Convection plays a role for the thermal structure of the solar…

Solar and Stellar Astrophysics · Physics 2011-12-14 Bernd Freytag , Matthias Steffen , Hans-Günter Ludwig , Sven Wedemeyer-Böhm , Werner Schaffenberger , Oskar Steiner

We solve the integral equation describing the propagation of light in an isothermal plane-parallel atmosphere of optical thickness $\tau^*$, adopting a uniform thermalization parameter $\epsilon$. The solution given by the ALI method,…

Astrophysics · Physics 2007-05-23 L. Chevallier , F. Paletou , B. Rutily

High-resolution (R ~ 90,000) spectra of 34 nearby, young Sun-like stars were analyzed using stellar atmosphere models to estimate effective photosphere temperatures, surface gravities, and the abundance of certain heavy elements (C, Na, Mg,…

Astrophysics · Physics 2009-11-07 E. J. Gaidos , G. Gonzalez

The chemical abundance measurements of host stars and their substellar companions provide a powerful tool to trace the formation mechanism of the planetary systems. We present a detailed high-resolution spectroscopic analysis of a young…

We constructed several sequences of classical Cepheid envelope models at solar chemical composition ($Y=0.28, Z=0.02$) to investigate the dependence of the pulsation properties predicted by linear and nonlinear hydrodynamical models on…

Astrophysics · Physics 2009-11-10 Silvia Petroni , Giuseppe Bono , Marcella Marconi , Robert F. Stellingwerf

We perform an extensive study of numerical convergence for hot-Jupiter atmospheric flow solutions in simulations employing a setup commonly-used in extrasolar planet studies, a resting state thermally forced to a prescribed temperature…

Earth and Planetary Astrophysics · Physics 2021-04-28 J. W. Skinner , J. Y-K. Cho

Several thermodynamic properties of ice Ih, II, and III are studied by a quasi-harmonic approximation and compared to results of quantum path integral and classical simulations. This approximation allows to obtain thermodynamic information…

Chemical Physics · Physics 2012-09-24 R. Ramirez , N. Neuerburg , M. -V. Fernandez-Serra , C. P. Herrero

A number of works infer radial temperature profiles of envelopes surrounding young stellar objects using several rotational transitions in a pixel-by-pixel or azimuthally-averaged basis. However, in many cases the assumption that the…

Astrophysics of Galaxies · Physics 2024-01-26 Robert Estalella , Aina Palau , Gemma Busquet

Current state-of-the-art computational modeling makes it possible to build realistic models of stellar convection zones and atmospheres that take into account chemical composition, radiative effects, ionization, and turbulence. The standard…

Solar and Stellar Astrophysics · Physics 2021-07-28 Irina N. Kitiashvili , Alan A. Wray

The holographic product formula is used to determine the general form taken by holographic spectral functions in the near-extremal hydrodynamic regime, with energy $\omega$, momentum $k$ and temperature $T$ much smaller than a hard scale…

High Energy Physics - Theory · Physics 2026-02-17 Edwan Préau

We use cosmological hydrodynamical simulations of Milky-Way-mass galaxies from the FIRE project to evaluate various strategies for estimating the mass of a galaxy's stellar halo from deep, integrated-light images. We find good agreement…

Using stellar structure calculations in the Hartle-Thorne approximation, we derive analytic expressions connecting the ellipticity of the stellar surface to the compactness, the spin angular momentum, and the quadrupole moment of the…

High Energy Astrophysical Phenomena · Physics 2015-06-16 Michi Baubock , Emanuele Berti , Dimitrios Psaltis , Feryal Ozel

We compare the mass cooling rates and cumulative cooled-down masses predicted by several semi-analytical (SA) cooling models with cosmological hydrodynamical simulations performed using the AREPO code (ignoring processes such as feedback…

Astrophysics of Galaxies · Physics 2019-03-20 Jun Hou , Cedric G. Lacey , Carlos. S. Frenk

State-of-the-art one-dimensional (1D) stellar evolution codes rely on simplifying assumptions, such as mixing length theory, in order to describe superadiabatic convection. As a result, 1D stellar structure models do not correctly recover…

Solar and Stellar Astrophysics · Physics 2019-08-07 Andreas Christ Sølvsten Jørgensen , Achim Weiss

We report the results of a systematic comparison between the vertically averaged model and the vertically explicit model of steady state, Keplerian, optically thick "alpha"-discs. The simulations have concerned discs currently found in…

Astrophysics · Physics 2016-08-30 Jean-Marc Huré , Frédéric Galliano

Estimating stellar masses for billions of galaxies in upcoming surveys requires methods that are both accurate and computationally efficient. We present a new approach using symbolic regression trained on a simulation to derive simple,…

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