Limb Darkening and Planetary Transits II: Intensity profile correction factors for a grid of model stellar atmospheres

TL;DR

This paper improves the accuracy of planetary transit analysis by calculating correction factors for limb darkening based on detailed stellar atmosphere models, reducing systematic errors in exoplanet measurements.

Contribution

It introduces a method to derive intensity profile correction factors from model stellar atmospheres for more precise transit modeling.

Findings

Correction factors vary with stellar parameters and orbital inclination.

Using detailed CLIV improves the accuracy of planetary radius measurements.

Systematic errors in transit analysis can be significantly reduced.

Abstract

The ability to observe extrasolar planets transiting their stars has profoundly changed our understanding of these planetary systems. However, these measurements depend on how well we understand the properties of the host star, such as radius, luminosity and limb darkening. Traditionally, limb darkening is treated as a parameterization in the analysis, but these simple parameterizations are not accurate representations of actual center-to-limb intensity variations (CLIV) to the precision needed for interpreting these transit observations. This effect leads to systematic errors for the measured planetary radii and corresponding measured spectral features. We compute synthetic planetary transits using model stellar atmosphere CLIV and corresponding best-fit limb-darkening laws for a grid spherically symmetric model stellar atmospheres. From these light curves we measure the differences in flux as a function of the star's effective temperature, gravity, mass, and the inclination of the planet's orbit.