LDTk: Limb Darkening Toolkit

TL;DR

LDTk is a Python toolkit that automates the calculation of custom stellar limb darkening profiles and coefficients, aiding precise modeling in exoplanet transits, eclipsing binaries, and other astrophysical phenomena.

Contribution

The paper introduces LDTk, a Python package that generates custom limb darkening profiles and coefficients with uncertainty propagation, integrated into existing modeling workflows.

Findings

Enables computation of limb darkening profiles with propagated uncertainties.

Provides limb-darkening coefficients with uncertainties for common models.

Allows direct integration into existing transit and eclipse modeling codes.

Abstract

We present a Python package LDTk that automates the calculation of custom stellar limb darkening (LD) profiles and model-specific limb darkening coefficients (LDC) using the library of PHOENIX-generated specific intensity spectra by Husser et al. (2013). The aim of the package is to facilitate analyses requiring custom generated limb darkening profiles, such as the studies of exoplanet transits--especially transmission spectroscopy, where the transit modelling is carried out for custom narrow passbands--eclipsing binaries (EBs), interferometry, and microlensing events. First, LDTk can be used to compute custom limb darkening profiles with uncertainties propagated from the uncertainties in the stellar parameter estimates. Second, LDTk can be used to estimate the limb-darkening-model specific coefficients with uncertainties for the most common limb-darkening models. Third, LDTk can be directly integrated into the log posterior computation of any pre-existing modelling code with minimal modifications. The last approach can be used to constrain the LD model parameter space directly by the LD profile, allowing for the marginalization over the LD parameter space without the need to approximate the constraint from the LD profile using a prior.