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Limb darkening measurements from TESS and Kepler light curves of transiting exoplanets

Maxted

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Abstract

Inaccurate limb-darkening models can be a significant source of error in the analysis of the light curves for transiting exoplanet and eclipsing binary star systems. To test the accuracy of published limb-darkening models, I have compared limb-darkening profiles predicted by stellar atmosphere models to the limb-darkening profiles measured from high-quality light curves of 43 FGK-type stars in transiting exoplanet systems observed by the Kepler and TESS missions. The comparison is done using the parameters h'1=I?(2/3) and h'2=h'1-I?(1/3)?, where I?(µ) is the specific intensity emitted in the direction µ, the cosine of the angle between the line of sight and the surface normal vector. These parameters are straightforward to interpret and insensitive to the details of how they are computed. I find that most (but not all) tabulations of limb-darkening data agree well with the observed values of h'1 and h'2?. There is a small but significant offset ?h'1˜0.006 compared to the observed values that can be ascribed to the effect of a mean vertical magnetic field strength ˜100?G that is expected in the photospheres of these inactive solar-type stars but that is not accounted for by typical stellar model atmospheres. The implications of these results for the precision of planetary radii measured by the PLATO mission are discussed briefly.

Citation

Maxted. (2023). Limb darkening measurements from TESS and Kepler light curves of transiting exoplanets. Monthly Notices of the Royal Astronomical Society, 3723-3735. https://doi.org/10.1093/mnras/stac3741

Acceptance Date Dec 16, 2022
Publication Date Mar 1, 2023
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Publisher Oxford University Press
Pages 3723-3735
DOI https://doi.org/10.1093/mnras/stac3741
Keywords methods: data analysis; planets and satellites: fundamental parameters; stars: atmospheres; stars: solar-type
Publisher URL https://academic.oup.com/mnras/article/519/3/3723/6958819

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