Atmosphere

For the spectral synthesis PySME needs a model atmosphere to perform the radiative transfer in. PySME does not come with a set of atmospheres in each distribution but instead uses the LFS (See Large File Server) to fetch only the required model atmosphere when run.

If you want to provide your own model atmosphere file, it should be present in ~/.sme/atmospheres/.

Each atmosphere model file describes a grid of models, on which we then linearly interpolate to the desired stellar parameters. Sometimes we dare extrapolate from this grid as well, but in that case, we always show a warnning.

Note that the atmosphere also contains a seperate set of stellar parameters, which is usually the same as that of the sme structure, but can be different, if for example the atmosphere is embedded, i.e. fixed, or has not been calculated yet.

The atmopshere object has the following fields

teff:

Effective Temperature in Kelvin

logg:

Surface Gravity in log(cgs)

monh:

Metallicity relative to the individual abundances

abund:

The individual abundances (see Abundance)

vsini:

Projected Rotational velocity in km/s

vmic:

Microturbulence velocity in km/s

vmac:

Macroturbulence veclocity in km/s

vturb:

Turbulent velocity in km/s

lonh:

? Metallicity

source:

Filename of the atmosphere grid

depth:

The depth scale to use for calculations. Either RHOX or TAU

interp:

The depth scale to use for interpolation. Either RHOX or TAU

geom:

The geometry of the atmopshere. Either Plane Parallel ‘PP’ or Spherical ‘SPH’.

method:

The method to use for interpolation. Either ‘grid’ for a model grid or ‘embedded’ if only a single atmosphere is given.

rhox:

‘Column density’ depth scale

tau:

‘Optical depth’ depth scale

temp:

Temperature profile

xna:

Number density of atoms, ions, and molecules in each depth

xne:

Number density of electrons in each depth