A shortcut to calculate SPAM limb-darkening coefficients

TL;DR

This paper introduces a new, simplified method for calculating stellar limb-darkening coefficients using the SPAM approach, providing a comprehensive grid of coefficients for various passbands based on STAGGER models.

Contribution

The paper presents a new, more straightforward algorithm for deriving limb-darkening coefficients, replacing the more complex SPAM procedure, and provides a publicly available grid of these coefficients.

Findings

ExoTETHyS produces limb-darkening coefficients comparable to the SPAM method.

The new algorithm simplifies the process of obtaining LDCs without sacrificing accuracy.

The data is available for multiple passbands and limb-darkening laws.

Abstract

We release a new grid of stellar limb-darkening coefficients (LDCs, using the quadratic, power-2 and claret-4 laws) and intensity profiles for the Kepler, U, B, V and R passbands, based on STAGGER model atmospheres. The data can be downloaded from Zenodo (doi:10.5281/zenodo.5593162). We compare the newly-released LDCs, computed by ExoTETHyS, with previously published values, based on the same atmospheric models using a so-called "SPAM" procedure. The SPAM method relies on synthetic light curves in order to compute the LDCs that best represent the photometry of exoplanetary transits. We confirm that ExoTETHyS achieves the same objective with a much simpler algorithm.