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We present results of three dimensional simulations of the uppermost part of the sun, at 3 stages of its evolution. Each model includes physically realistic radiative-hydrodynamics (the Eddington approximation is used in the optically thin…

Astrophysics · Physics 2007-05-23 F. J. Robinson , P. Demarque , S. Sofia , K. L. Chan , Y. -C. Kim , D. B. Guenther

The thermal properties of hydrodynamical simulations of galaxy clusters are usually compared to observations by relying on the emission-weighted temperature T_ew, instead of on the spectroscopic X-ray temperature T_spec, which is obtained…

Astrophysics · Physics 2009-11-10 E. Rasia , P. Mazzotta , S. Borgani , L. Moscardini , K. Dolag , G. Tormen , A. Diaferio , G. Murante

We have determined new statistical relations to estimate the fundamental atmospheric parameters of effective temperature and surface gravity, using MK spectral classification, and vice versa. The relations were constructed based on the…

Solar and Stellar Astrophysics · Physics 2020-09-30 O. Yu. Malkov , D. A. Kovaleva , S. G. Sichevsky , G. Zhao

One-dimensional (vertical) models of planetary atmospheres typically balance the net solar and internal energy fluxes against the net thermal radiative and convective heat fluxes to determine an equilibrium thermal structure. Thus,simple…

Earth and Planetary Astrophysics · Physics 2019-04-17 Juan P. Tolento , Tyler D. Robinson

We report the discovery of a well-defined correlation between B-band face-on central optical depth due to dust, \tau^f_B, and the stellar mass surface density, \mu_{*}, of nearby (z < 0.13) spiral galaxies: log(\tau^f_B) =…

We used a series of COBOLD hydrodynamical model atmospheres covering stellar objects from white dwarfs to red giants to derive theoretical estimates of the photometric and photocentric stellar variability in wavelength-integrated light…

Astrophysics · Physics 2007-05-23 F. Svensson , H. -G. Ludwig

Main sequence, solar-like stars (M < 1.5 Msun) have outer convective envelopes that are sufficiently thick to affect significantly their overall structure. The radii of these stars, in particular, are sensitive to the details of…

Solar and Stellar Astrophysics · Physics 2018-12-26 F. Spada , P. Demarque , S. Basu , J. D. Tanner

We compare predictions of cooled masses and cooling rates from three stripped-down Semi-Analytic Models (SAMs) of galaxy formation with the results of N-body+SPH simulations with gas particle mass of 3.9x10^6 Msun, where radiative cooling…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 Pierluigi Monaco , Andrew Benson , Gabriella De Lucia , Fabio Fontanot , Stefano Borgani , Michael Boylan-Kolchin

Long-baseline interferometry at optical and near-infrared wavelengths is an emerging technology which is quickly becoming a useful tool to investigate stellar atmospheres and to compare observations with models. Stellar atmosphere models…

Astrophysics · Physics 2007-05-23 Markus Wittkowski

Spectra of late-type stars are usually analyzed with static model atmospheres in local thermodynamic equilibrium (LTE) and a homogeneous plane-parallel or spherically symmetric geometry. The energy balance requires particular attention, as…

Astrophysics · Physics 2009-11-06 Carlos Allende Prieto , Paul S. Barklem , Martin Asplund , Basilio Ruiz Cobo

Since about 25 years ago work has been dedicated to the development of hydrodynamical model atmospheres for cool stars (of A to T spectral type). Despite their obviously sounder physical foundation in comparison with standard hydrostatic…

Astrophysics · Physics 2007-05-23 H. -G. Ludwig , A. Kucinskas

Three-dimensional radiation-hydrodynamics (3D RHD) simulations of stellar surface convection provide valuable insights into many problems in solar and stellar physics. However, almost all 3D near-surface convection simulations to date are…

Solar and Stellar Astrophysics · Physics 2023-09-13 Yixiao Zhou , Anish M. Amarsi , Victor Aguirre Børsen-Koch , Klara G. Karlsmose , Remo Collet , Thomas Nordlander

Space-based observations of solar-like oscillations present an opportunity to constrain stellar models using individual mode frequencies. However, current stellar models are inaccurate near the surface, which introduces a systematic…

Solar and Stellar Astrophysics · Physics 2015-06-22 Warrick H. Ball , L. Gizon

We describe a new method for the computation of opacity distribution functions (ODFs) useful to calculate one-dimensional model atmospheres in local thermal equilibrium (LTE). The new method is fast enough to be applied on current…

Astrophysics · Physics 2007-05-23 F. Kupka , N. E. Piskunov

Context. Semi-grey atmospheric models (with one opacity for the visible and one opacity for the infrared) are useful to understand the global structure of irradiated atmospheres, their dynamics and the interior structure and evolution of…

Earth and Planetary Astrophysics · Physics 2015-06-18 Vivien Parmentier , Tristan Guillot

Based on detailed 2D and 3D numerical radiation-hydrodynamics (RHD) simulations of time-dependent compressible convection, we have studied the dynamics and thermal structure of the convective surface layers of a prototypical late-type…

Astrophysics · Physics 2009-11-07 H. -G. Ludwig , F. Allard , P. H. Hauschildt

We construct a new set of self-consistent analytical disk models by taking into account both viscous and radiative sources of thermal energy. We analyze the non-isothermal structure of the disk across the mid-plane for optically thick…

Astrophysics · Physics 2008-11-26 Pascale Garaud , Douglas N. C. Lin

In the present work we compare in detail some of the major theoretical libraries with observations, aiming at detecting weaknesses and strengths from the stellar population modelling point of view. We compared model predictions and…

Astrophysics · Physics 2009-11-13 Lucimara Martins , Paula Coelho

The Hipparcos mission has made it possible to constrain the positions of nearby field stars in the colour-magnitude diagram with very high accuracy. These positions can be compared with the predictions of stellar evolutionary calculations…

Astrophysics · Physics 2009-09-17 Carlos Allende Prieto , David L. Lambert

Simplified, one-dimensional models are necessary to model convection in the context of stellar evolution. By including the non-local effects of convection, turbulent convection models describe convection in a more physical way compared to…

Solar and Stellar Astrophysics · Physics 2026-05-20 T. A. M. Braun , F. Ahlborn , F. Kupka , A. Weiss