Korg.jl

Korg is a package for computing stellar spectra from 1D model atmospheres and linelists assuming local thermodynamic equilibrium. It can be used with Julia or Python. Here's some things it can do:

Computing spectra from Teff, logg, abundances, etc.
Fitting whole spectra or individual lines via synthesis or equivalent widths
Excitation-ionization balance from equivalent width data
Model atmosphere interpolation, parsing and using atmosphere files (MARCS)
Parsing and using linelists in VALD, Kurucz, MOOG, ExoMol, and Turbospectrum formats, with several defaults built-in.
Automatic differentiaion (via ForwardDiff.jl)
Synthesis with arbitrary abundances/solar abundance scales, with several defaults built-in.

After installing Korg, get started by looking at the top-level functions or the tutorial notebooks.

Example

(Python version below)

using Korg, PyPlot

wls, flux, continuum = synth(
    Teff=5000, # effective temperature of 5000 Kelvin
    logg=4.32, # surface gravity of 10^(4.32) cm/s²
    m_H=-1.1,  # metallicity, [m/H]. Overridden for individual elements by alpha_H and individual abundances
    C=-0.5,    # The Carbon abundance, [C/H].  Works for anything from He to U.
    linelist=Korg.get_GALAH_DR3_linelist(),
    wavelengths=(5850, 5900)
)

# plot
figure(figsize=(12, 4))
plot(wls, flux, "k-")
xlabel(L"$\lambda$ [Å]")
ylabel(L"$F_\lambda/R_\mathrm{star}^2$ [erg s$^{-1}$ cm$^{-5}$]");

See the documentation for synth, or the documentation for synthesize for advanced usage.

Code papers (please cite these if you use Korg):

Korg: A Modern 1D LTE Spectral Synthesis Package. This is also a good overview of how spectral synthesis works, the inputs and outputs, etc.
Korg: fitting, model atmosphere interpolation, and Brackett lines

Tutorials:

Getting help

If you are having trouble using or installing Korg, please get in touch by opening a GitHub issue (preferred), or sending Adam an email.

You can also call Korg from python

See the documentation for setup instructions.

from juliacall import Main as jl
jl.seval("using Korg"); Korg = jl.Korg

# calling Korg.synth is exactly the same as in Julia.
wls, flux, continuum = Korg.synth(
    Teff=5000,
    logg=4.32,
    m_H=-1.1,
    C=-0.5,
    linelist=Korg.get_GALAH_DR3_linelist(),
    wavelengths=(5850, 5900)
)

Multithreading

Korg can use multithreading to speed up line opacity calculation, the most expensive step for syntheses. To use it launch Julia with more than one thread, using the -t command-line argument, or by setting the $JULIA_NUM_THREADS environment variable.