Add support for other stellar atmosphere models

[galaxyumi]

Currently the BEAST is using Kurucz model for LTE and TLUSTY model for non-LTE.

[mfouesneau]

You can check pystellib [http://mfouesneau.github.io/docs/pystellibs/] maybe a good start?

[lcjohnso]

List of atmosphere models to try adding:

• Aringer for AGBs (see also: https://github.com/karllark/beast/issues/25)
• BT-Settl for pre-MS

Other specific requests? @galaxyumi?

[lcjohnso]

Update: work to include BT-Settl is underway.

Adding Aringer will be more difficult, requiring that additional data columns are harvested from the stellar models (e.g., C/O ratio, others?) to match appropriate atmospheres to each grid point.

[lcjohnso]

BT-Settl and Munari libraries have been added via PR https://github.com/BEAST-Fitting/beast/pull/126.

Still ToDo: Aringer for PARSEC+COLIBRI, and added documentation about differences between various speclib choices.

[galaxyumi]

It would be great if we add the WM basic model for hot stars.

[karllark]

@galaxyumi : can you provide references and locations for an appropriate grid of spectra for WM basic? Also, can you provide a bit more info? Like, would this be a drop in replacement for the TLusty models? I am not all that familiar with the WM basic models.

[galaxyumi]

Reference for the WM-basic is Pauldrach+98 and Pauldrach+01. Here is the link we can download their original spectra: http://www.usm.uni-muenchen.de/people/adi/Programs/Programs.html. And the Cloudy provide rebinned spectral grid as well (http://www.nublado.org/wiki/StellarAtmospheres). I do not know the very details about the WM-basic. But the main difference between the TLUSTY and WM-basic is the geometry. While the TLUSTY solve the non-LTE solution for the plane-parallel geometry, the WM-basic includes a spherically expanding stellar wind. I don't know about other science cases, but if ones about O/B stars, it would be good to have an option to pick the WM-basic for the non-LTE grid.

[karllark]

A brief look at the grid for WM-basic indicates that it is not as large as the TLUSTY grid.
Would be useful to have direct comparisons between the models that overlap between WM-basic and TLUSTY. Plots of spectra. Maybe the WM-basic can replace the TLUSTY models where they exist and we can use the TLUSTY models for the rest of the non-LTE cases? Very limited in abundances too.

[galaxyumi]

I like the idea that replacing the TLUSTY models with the WM-basic where they exist for in the non-LTE regime. I have seen many O/B star studies preferring the WM-basic models.

[karllark]

@galaxyumi : Is this something that you would like to work on?

[galaxyumi]

Sure. I will try to find time to work on this soon.

[karllark]

Great!

[karllark]

Closing this issue as a few new atmosphere grids have been added. Adding additional should be done with an issue for each specific grid to be added. E.g., see #180.