Switch and choose a stellar spectrum¶

PROTEUS supports four stellar spectrum sources, selected via star.mors.spectrum_source in your config file. This guide walks through each option and when to use it.

Which source should I use?¶

When in doubt, use "phoenix". It covers the widest range of stellar parameters and is downloaded automatically.

Option 1: Solar spectrum¶

Use this when your host star is the Sun (modern or at a past/future age).

[star.mors]
    spectrum_source = "solar"
    star_name       = "sun"       # modern NREL solar spectrum

To use a young or future Sun, choose one of the VPL spectra by Claire et al. (2012):

[star.mors]
    spectrum_source = "solar"
    star_name       = "Sun3.8Ga"  # Sun as it was 3.8 Gyr ago (age ~ 800 Myr)

Available star_name values for the solar source (case-insensitive):

Downloading solar spectra¶

Solar spectra are downloaded automatically on first run. You can also pre-download manually with the CLI:

proteus get solar

Option 2: MUSCLES / Mega-MUSCLES observed spectrum¶

Use this when your host star is a real star covered by the MUSCLES or Mega-MUSCLES surveys. These spectra include observed UV and X-ray flux, which matters most for photochemistry and escape calculations.

[star.mors]
    spectrum_source = "muscles"
    star_name       = "trappist-1"

The full list of available stars is in the Reference data page. star_name is case-insensitive; the names listed in the reference catalog are the canonical forms (e.g. gj551 for Proxima Centauri, v-eps-eri for Epsilon Eridani).

Downloading MUSCLES spectra¶

Spectra are downloaded automatically on first run. You can also pre-download manually with the CLI:

# List all available star names
proteus get muscles --list

# Single star
proteus get muscles --star trappist-1

# All available stars
proteus get muscles --all

Option 3: PHOENIX synthetic spectrum¶

Use this when no observed spectrum exists for your target star. PHOENIX provides a grid of synthetic spectra over a wide range of stellar parameters.

[star.mors]
    spectrum_source = "phoenix"

By default, Teff, log_g, and radius are derived from the stellar mass via the MORS stellar evolution tracks, and metallicity defaults to solar. To override any of these:

[star.mors]
    spectrum_source  = "phoenix"
    phoenix_Teff     = 3500       # effective temperature [K]
    phoenix_log_g    = 5.0        # surface gravity [log10 cgs]
    phoenix_radius   = 0.12       # stellar radius [R_sun]
    phoenix_FeH      = 0.0        # metallicity [Fe/H]; 0.0 = solar
    phoenix_alpha    = 0.0        # alpha enhancement; 0.0 = solar

Downloading PHOENIX spectra¶

PHOENIX spectra are downloaded automatically on first run. To pre-download for a specific parameter combination, --feh and --alpha are required; --teff is optional but helps select the correct alpha availability:

proteus get phoenix --feh 0.0 --alpha 0.0 --teff 3500

Option 4: Custom spectrum file¶

Use this when you have your own spectrum file that PROTEUS should use directly, regardless of what spectrum_source is set to.

[star.mors]
    star_path = "/absolute/path/to/my_spectrum.txt"
    # or, if the file is inside $FWL_DATA:
    star_path = "$FWL_DATA/stellar_spectra/my_spectrum.txt"

Your spectrum file must be:

• A two-column ASCII file (comments with #)
• Column 1: wavelength in nm
• Column 2: flux in erg s\(^{-1}\) cm\(^{-2}\) nm\(^{-1}\), scaled to 1 AU