lte-codes

Sterne

Spectrum

Sfit

SCL

grids

STERNE MODELS

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In 2006, Behara and Jeffery introduced a new file format for the model atmospheres produced by STERNE and used by SPECTRUM and SFIT. The design is defined by keywords and data. The objects of the new format are to:
be consistent with other i/o in the packages,
be easily readable,
be flexible and extensible,
retain the full model history,
allow depth-dependent descriptions of composition, and
allow transformations of physical quantities (eg logs, units)
The models may be read in using subroutine "stn_readmodel". Data structures are provided by module "stn_model". Both in the lte-codes-XX library "dp". It is emphasized that not all fields are required for a useable description of the model atmosphere, and that new fields can be easily incorporated.

Keywords and associated structures

Syntax

* : mandatory keyword
context.keyword    < variable > : description
context.keyword    [ option 1 | option 2 | option 3 ]   : expand options
array.keyword      : read in following free-format array --
< var₁, var₂, ..., var₃ >
In general -- order does not matter. However, arrays, as indicated by some Structure and Spectrum keywords, need their dimensions defined before use. Data for array structures must commence on a new line.

Basic Parameters

model.origin    < originating program >
model.date    < date computed >
model.label    < identifier >
model.composition    [ homogeneous | stratified ]

*model.teff    < T_eff >
*model.gravity    < log g >
model.frache    < H/(H+He) >
model.febyh    < [Fe/H] > : metallicity, default 0.0 dex
model.albyfe    < [alpha/Fe] > : alpha enhancement, default 0.0 dex

model.lambda_ref    <lambda_ref >
model.nelems    < N_elements >
model.nstrat    < N_{el_strat} > :    Number of elements treated as stratified
model.layers    < N_depth >

opacity.bf_source    [ OP | KIEL ]
opacity.bb_source    [ SAM | ODF ]
opacity.bb_int    < delta lambda >
opacity.vturb    < v_turb >

units.teff    [ kelvin ]
units.gravity   [ log_cgs ]
units.vturb    [ cm/s ]
units.lambda_ref    [ Angstrom ]

Composition

*abundance    < elem > < abund >
-- repeat for each element, assume solar scaled by [Fe/H],[alpha/Fe] otherwise
structure.abundance    < elem > : ( needs N_depth )
< ab_elem,1, ab_elem,2, ..., ab_elem,Ndepth >
-- repeat for each element with non-uniform distribution
units.abundance    [ number_fraction ]

Structure

*structure.tau_ref    : ( needs N_depth )
< tau_ref,1, tau_ref,2, ..., tau_ref,Ndepth >
structure.opac_ref    : ( needs N_depth )
< kappa_ref,1, kappa_ref,2, ..., kappa_ref,Ndepth >
*structure.temp    : ( needs N_depth )
< T₁, T₂, ..., T_Ndepth>
*structure.pgas    : ( needs N_depth )
< P_gas,1, P_gas,2, ..., P_gas,Ndepth >
structure.pel    : ( needs N_depth )
< P_el,1, P_el,2, ..., P_el,Ndepth >
structure.grad    : ( needs N_depth )
< g_rad,1, g_rad,2, ..., g_rad,Ndepth >
structure.mass    : ( needs N_depth )
< m₁, m₂, ..., m_Ndepth >
structure.depth    : ( needs N_depth )
< z₁, z₂, ..., z_Ndepth >

units.tau_ref    [ log ]
units.opac_ref    [ log ]
units.temp    [ kelvin ]
units.pgas    [ log_dyn ]
units.pel    [ log_dyn ]
units.grad    [ log_cm/s^2 ]
units.mass    [ log_g ]
units.depth    [ log_cm ]

Emergent Spectrum

spectrum.length    < N_wave >
spectrum.wave    : ( needs N_wave )
< lambda₁, lambda₂, ..., lambda_Nwave >
spectrum.flux    : ( needs N_wave )
< F_lambda,1, F_lambda,2, ..., F_lambda,Nwave >
spectrum.fcont    : ( needs N_wave )
< F_cont,1, F_cont,2, ..., F_cont,Nwave >

units.wave    [ Angstrom ]
units.flux    [ erg/cm^2/A ]
units.fcont    [ erg/cm^2/A ]

Example

An example of a homegenoeus model atmosphere with Teff=20000 K, log g=3.0, is given here.

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This page is maintained by: 
Simon Jeffery (csj at arm.ac.uk) 
Last modified: Sep 14, 2006