Coupling to PROTEUS

This page is the practical recipe for using MORS inside a PROTEUS coupled run: which configuration blocks matter, what each setting does, and which combinations are valid. For how MORS behaves once it is coupled, the track model, the per-iteration quantities, and the spectral synthesis, see Coupling to PROTEUS (explanation).

The MORS wrapper lives in the PROTEUS repository (src/proteus/star/wrapper.py), not in MORS itself. This page documents the MORS side of the contract: the [star] and [star.mors] configuration that the wrapper reads.

Minimal [star] block

MORS is enabled by selecting it as the star module and giving the host-star mass:

[star]
module = "mors"        # use MORS for stellar evolution
mass   = 1.0           # stellar mass [M_sun]

[star.mors]
tracks          = "spada"     # "spada" or "baraffe"
age_now         = 4.567       # current stellar age [Gyr]
rot_pcntle      = 50.0        # rotation percentile (0-100)
spectrum_source = "solar"     # "solar", "muscles", or "phoenix"
star_name       = "sun"       # required for "solar" and "muscles"

Choosing the tracks

star.mors.tracks selects the stellar-evolution grid:

Use "spada" for a rotation-driven XUV history (the usual choice for escape studies). Use "baraffe" when you only need bolometric evolution over a wider mass range and do not need XUV or rotation.

Setting the initial rotation

Rotation drives the XUV history on Spada tracks. Set it with exactly one of two options:

• star.mors.rot_pcntle: a rotation percentile in the 1 Myr distribution (0 to 100). The reference age is fixed at 1 Myr, matching mors.Percentile(). A percentile of 5 is a slow rotator, 50 the median, 95 a fast rotator.
• star.mors.rot_period: a rotation period in days at the current stellar age star.mors.age_now.

Exactly one of rot_pcntle and rot_period must carry a value. rot_pcntle defaults to 50 (the median rotator), so leaving both keys out is valid and selects the median rotation without raising an error. Setting both to a value raises a configuration error, and so does nulling rot_pcntle (setting rot_pcntle = "none") while leaving rot_period unset. This check runs for every MORS configuration regardless of the chosen tracks. Baraffe tracks have no rotation model, so the value does not affect the evolution, but the setting is still validated.

Choosing the reference spectrum

star.mors.spectrum_source selects the modern reference spectrum that the historical spectra are scaled from:

For "solar" and "muscles", set star.mors.star_name to the target star (for the solar reference, star_name = "sun"). "phoenix" instead builds the spectrum from stellar parameters and does not need star_name. PROTEUS rescales the chosen spectrum to the planet's orbital separation. Fuller detail on stellar spectra is in the PROTEUS data reference.

Common pitfalls

• Both rot_pcntle and rot_period set. Setting both to a value is rejected for any tracks (including Baraffe). Because rot_pcntle defaults to 50, leaving both keys out is accepted and gives the median rotator; the "neither set" error appears only if you null rot_pcntle without setting rot_period.
• age_now missing or non-positive. The current stellar age must be greater than zero; it is given in Gyr.
• Expecting XUV from Baraffe tracks. Baraffe tracks provide no XUV; the XUV instellation is set to zero. Use Spada tracks for escape-driving XUV.
• Mass outside the track range. The mass is clipped with a warning, so the simulated star may differ from the configured one. Check the log if the star mass is near a track limit.

Next step

See Coupling to PROTEUS (explanation) for the track model, the quantities MORS updates each iteration, and how the historical spectrum is synthesised.