About

stagger_ov

Intensity maps for the Sun, TO, RG and dwarf star with decreasing metallicity. Note the difference in the intensity contrast for the different models with metallicity.

 

The Stagger-grid project is a collaborative effort to generate a grid of realistic, 3D, time-dependent, hydrodynamic model atmospheres of cool stars for a range of stellar parameters. The grid is used to produce synthetic spectra (of spectral type F, G, K, M) and colors, make predictions for various observational diagnostics, as well as, study stellar surface convection and asteroseismic properties across the Hertzsprung-Russell diagram.

Individual data files are available for download for the respective applications. If you refer to the Stagger-grid, please use Magic et al. 2013a as the reference.

 

 


Overview

Figure: Showing the Hertzsprung-Russell diagram, to illustrate the stellar parameter range of the Stagger-grid. The additional four standard stars are also shown (squares).

We cover various evolutionary stages from main-sequence stars, over turnoff-star to red-giant stars.

The stellar parameter ranges:

  • effective temperature Teff, from 4000 to 7000K in steps of 500K
  • surface gravity log g, from 1.5 to 5.0 in steps of 0.5 dex
  • metallicity [Fe/H], from −4.0 to +0.5 in steps of 0.5 and 1.0 dex.

Furthermore, besides the Sun and Procyon we have custom made simulations for four additional standard stars, HD 84937, HD 140283, HD 122563 and G 64-12.

 

 

 

 


Specifications

mesh

The numerical mesh of the solar simulation box. The density and temperature are defined at cell center (black dot), the momenta at the cell face (red circle), and the magnetic field at the cell edges.

  • Code: Stagger-code (Nordlund & Galsgaard 1995); staggered Eulerian mesh; sixth-order explicit finite-difference scheme; fifth-order interpolation scheme; stabilized by hyperviscosity
  • Geometry: box-in-a-star” setup, vertically open, horizontally periodic, mesh resolution: 2403, vertical non-equidistant spacing with higher resolution at the photosphere
  • Radiative transfer: opacity binning  method with 12 bins and 9 angles on long characteristics
  • Opacities: up-to-date atomic data, MARCS package and KURUCZ line lists
  • Equation-of-state: Mihalas et al. 1988

 

 

 

 


Papers

  1. The Stagger-grid – I. Methods and general properties
  2. The Stagger-grid – II. Horizontal and temporal averaging and spectral line formation
  3. The Stagger-grid – III. The relation to mixing length convection theory
  4. The Stagger-grid – IV. Limb darkening coefficient
  5. The Stagger-grid – V. Fe line shapes, shifts and asymmetries
  6. The Stagger-grid – VI. Properties of stellar granulation

 

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