The Stagger-grid: A grid of 3D stellar atmosphere models - I. Methods and general properties

By Z. Magic, R. Collet, Martin Asplund, R. Trampedach, W. Hayek, A. Chiavassa, Robert F. Stein, Åke Nordlund. 2013

188 citations recorded by the source corpus.

Aims. We present the Stagger-grid, a comprehensive grid of time-dependent, three-dimensional (3D), hydrodynamic model atmospheres for late-type stars with realistic treatment of rad iative transfer, covering a wide range in stellar parameter s. This grid of 3D models is intended for various applications besides studies of stellar convection and atmospheres per se, including stellar parameter determination, stellar spectroscopy and abundance analysis, asteroseismology, calibration of stellar evolution mo dels, interferometry, and extrasolar planet search. In this introductory paper, w e describe the methods we applied for the computation of the grid and discuss the general properties of the 3D models as well as of their temporal and spatial averages (here denotedh 3Di models). Methods. All our models were generated with the Stagger-code, using realistic input physics for the equation of sta te (EOS) and for continuous and line opacities. Our∼ 220 grid models range in effective temperature, Teff, from 4000 to 7000 K in steps of 500 K, in surface gravity, log g, from 1.5 to 5.0 in steps of 0.5 dex, and metallicity, [Fe/H], from−4.0 to +0.5 in steps of 0.5 and 1.0 dex. Results. We find a tight scaling relation between the vertical velocit y and the surface entropy jump, which itself correlates with the constant entropy value of the adiabatic convection zone. The range in intensity contrast is enhanced at lower metallici ty. The granule size correlates closely with the pressure scale height sampled at the depth of maximum velocity. We compare theh 3Di models with currently widely applied one-dimensional (1D) atmosphere models, as well as with theoretical 1D hydrostatic models generated with the same EOS and opacity tables as the 3D models, in order to isolate the effects of using self-consistent and hydrodynamic modeling of convection, rather than the classical mixing length theory (MLT) approach. For the first time, we are able to quantify s ystematically over a broad range of stellar parameters the uncertainties of 1D models arising from the simplified treatment of physics, in particular convective energy transport. In agreement with previous fin dings, we find that the di fferences can be rather significant, especially for metal-poor stars.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/acd4aeec8988eb6ad639b2de568f6bb35c16ef2f

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Citations in the corpus

Synthetic stellar photometry – I. General considerations and new transformations for broad-band systems (2014, background): “…still largely unexplored (Kučinskas et al. 2005, 2009; Casagrande 2009), but hopefully the recent advent of hydrodynamic grids of model atmosphere (Beeck et al. 2013; Magic et al. 2013; Tremblay et al. 2013; Tanner et al. 2013) will soon make such studies possible. c© 0000 RAS, MNRAS 000, 000–000”
A new correction of stellar oscillation frequencies for near-surface effects (2014, background): “Recent simulations (e.g. Beeck et al. 2013; Magic et al. 2013; Trampedach et al. 2013) should allow similar studies to be carried out for a range of stellar surface properties and allow some forward computation of the expected location and scale of the surface correction.”
Spectroscopic analysis of DA white dwarfs with 3D model atmospheres (2013, background): “We have no indication that our 3D simulations are inaccurate, and a similar dynamic cooling effect is predicted from 3D simulations of metal-poor dwarfs and giants computed with different codes (Asplund et al. 1999; González Hernández et al. 2010; Magic et al. 2013).”
Near-Field Cosmology with Extremely Metal-Poor Stars (2015, background): “…(3D) model atmosphere and non-LTE (hereafter NLTE) formalisms, rather than the 1D/LTE approximations, see Asplund (2005), and references therein; examples of recent developments in these areas include Lind et al. (2012), Ludwig & Kučinskas (2012), Tremblay et al. (2013) and Magic et al. (2013).”
The elemental composition of the Sun - I. The intermediate mass elements Na to Ca (2014, background): “2 To describe the full monochromatic opacity variation as accurately as possible, during the simulation the radiative transfer was solved for 12 opacity bins sorted in both wavelength and opacity strength (Nordlund 1982; Pereira et al. 2013; Magic et al. 2013).”
The GALAH Survey: Second Data Release (2018, methodology): “…advances in a range of areas, including template matching (Jofré et al. 2010), automated machine learning (Ness et al. 2015), atmospheric modelling (Magic et al. 2013), spectral line formation (Amarsi et al. 2016a) and internal instrument calibrations (BlandHawthorn et al. 2017; Kos et al. 2018).”