Usage

The ESTER calculates the axisymmetric structure and mean flows of an isolated (non-magnetic) rotating star. It uses realistic physics (tabulated opacities and EOS like those of OPAL) and completely accounts for the deformation of the star. The mean flows are calculated self-consistently in the limit of low viscosity, so there is no need to impose an arbitrary prescription for the differential rotation of the star. Surface convection is not included yet, so the computations are limited to early-type stars, that is to stars with mass typically above <math>\sim 2M_\odot</math> .

Presently, chemical evolution is not included, but it can be faked by tweaking the fractional abundance of hydrogen in the convective core.

For a detailed description of the physics involved in the models, see Rieutord & Espinosa Lara 2013 (arXiv:1208.4926, LNP 865, p.49) and Espinosa Lara & Rieutord 2013 (arXiv:1212.0778, in A&A 552, A35). The code is still in development, so new functionality will be added in future versions.

Table of Contents Running ESTER Configuration Files Simulation Parameters 1D Parameters 2D Parameters

Running ESTER

To execute the program, use the following syntax:

$ ester command [options]

The available commands are:

• 1d: calculate the structure of a 1D non-rotating star
• 2d: calculate the structure of a 2D star
• output: generate a custom output file
• info: get information about a model file
• help: get help

Configuration Files

The main configuration file is located at $prefix/share/ester/config/star.cfg (replace $prefix with yours, see configure). This file contains the main options for the program, which are:

• maxit (default: <math>200</math>): maximum number of iterations. After maxit iterations, the program exits normally and the output file is saved, even if it has not completely converged.
• minit (default: <math>1</math>): minimum number of iterations. It may occur that the value of the error for the first iteration is not representative. With this parameter we force the solver to do at least minit iterations. This parameter is superseded by maxit, for example if maxit=5 and minit=10, the solver will do only 5 iterations.
• tol (default: <math>1e^{-8}</math>): the relative tolerance for checking the convergence of the model.
• newton_dmax (default: <math>0.5</math>): After one step of the Newton's method, the maximum relative change allowed for a variable is given by newton_dmax. If necessary the iteration is relaxed by a parameter <math>h</math>: <math>\vec x^{N+1}=\vec x^N+h \delta\vec x^N</math> according to this value. This parameter can be used to stabilize the convergence when the initial estimation is far from the solution.
• output_file (default: star.out): name of the output file.
• output_mode(default: b): type of the output file (b for binary and t for text output).
• verbose (default: 1): level of verbosity, from 0 (quiet) to 4.
• plot_device (default: /XSERVE): plotting device for PGPLOT, see PGPLOT's documentation for details. For output in a X window use /XSERVE. To disable the graphic output use /NULL.
• plot_interval (default: 10): minimum time in seconds to update the graphic output.

These options can be specified in the file $prefix/share/ester/config/star.cfg in the form option_name=option_value (one per line) and on the command line as -option_name option_value. The options specified on the command line have precedence over those specified in the configuration file.

The following additional options can be used on the command line:

• -input_file infile: use the file infile as the starting point for the iteration.
• -i infile: same as -input_file infile.
• -o outfile: same as -output_file outfile.
• -param_file file: where file contains the parameters of the stellar model to be calculated (see input parameters).
• -p file: same as -param_file file.
• -ascii: same as -output_mode t.
• -binary (-b): same as -output_mode b.
• -noplot: same as -plot_device /NULL.
• -v n: same as -verbose n.

Simulation Parameters

1D Parameters

• ndomains: the number of sub-domains to be used.
• npts: the number of points in each sub-domain (comma separated list or a single value).
• M:
• X:
• Z:
• Xc:
• surff:
• Tc:
• pc:
• opa:
• eos:
• nuc:
• atm:
• core_convec:
• min_core_size:

When input parameters are omitted, the default (in $prefix/share/ester/1d_default.par) are used.

2D Parameters