Korg.jl Interpolator¶

The KorgSpectrumEmulator is a simple interpolator for a grid of model atmospheres generated with the Korg.jl package.

The line list used for this grid is the GALAH DR3 line list.

Basic Usage¶

The interpolator can be used to generate synthetic spectra based on a grid of model atmospheres:

from spice.spectrum.spectrum_korg import KorgSpectrumEmulator

k = KorgSpectrumEmulator()

The KorgSpectrumEmulator is downloaded from huggingface to a selected cache location. It’s around 10 GBs, so if you want to change the location of the HuggingFace cache, make sure to set the environment variable:

export HF_HOME=/your/cache/location

A small grid (~300 MB) will be downloaded by default. To switch to a larger grid (~10 GB), pass the argument of grid_type='regular'.

Using the Interpolator with a Mesh Model¶

The interpolator can be used to generate synthetic spectra based on a mesh model, just like other spectrum models in SPICE.

from spice.models import IcosphereModel
from spice.spectrum import simulate_observed_flux
import jax.numpy as jnp

base_temp = 5700
wavelengths = jnp.linspace(5650, 5910, 10000)
m = IcosphereModel.construct(1000, 1., 1., k.to_parameters(dict(teff=base_temp)), k.stellar_parameter_names)
non_rotated_spec = simulate_observed_flux(k.intensity, m, jnp.log10(wavelengths))

This code snipped will produce a synthetic spectrum for a 5700 K star, without any rotational effects.

a synthetic spectrum without rotational effects

To add rotational effects, we can use the add_rotation function from the spice.models.mesh_transform module.

from spice.models.mesh_transform import add_rotation, evaluate_rotation

m_r = add_rotation(m, rotation_velocity=10.)
m_rotated = evaluate_rotation(m_r, 0.)
rotated_spec = simulate_observed_flux(k.intensity, m_rotated, jnp.log10(wavelengths))