Limb-darkening coefficients for four-term and power-2 laws for the JWST mission adopting spherical PHOENIX models at high resolution

Aims. Modeling observations of transiting exoplanets or close binary systems by comparing the observations with theoretical light curves requires precise knowledge of the distribution of specific intensities across the stellar disk. We aim to facilitate this type of research by providing extensive tabulations of limb-darkening coefficients for 11 frequently used near- and mid-infrared passbands on the NIRCam, NIRISS, and NIRSpec instruments installed on board the James Webb Space Telescope. Methods. The calculation of the limb-darkening coefficients was based on spherically symmetric atmosphere models from the PHOENIX series, with a high spectral resolution (approximately 10 6 wavelengths), and covering the wavelength range 0.1-6.0 μ m. The models were computed for solar composition, and a microturbulent velocity of 1.0 kms -1 . We adopted two of the more accurate parametrizations for the coefficients: the four-term law, and the power-2 law. We applied the Levenberg-Marquardt least-squares minimization method, with a strategy to determine the critical value, μ crit , of the cosine of the viewing angle near the limb that is designed to improve numerical accuracy. Results. The limb-darkening coefficients were derived based on a total of 306 atmosphere models covering an effective temperature range of 2400-7800 K, and a log g interval between 3.0 and 5.5. We discuss the quality of the fits to the specific intensities provided by the power-2 and four-term laws, as well as by the often-used quadratic law. Based on a comparison, we recommend the use of the four-term or power-2 laws, in that order of preference.

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Publication Details

Journal
Astronomy and Astrophysics
Published
2025-06-11
DOI
https://doi.org/10.1051/0004-6361/202554770
Citations
1
Primary Topic
Geophysics and Gravity Measurements
Type
article
Field-Weighted Citation Impact
1.79

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article

Limb-darkening coefficients for four-term and power-2 laws for the JWST mission adopting spherical PHOENIX models at high resolution

Guillermo Torres, A. Claret, P. H. Hauschildt
1 citations
Astronomy and Astrophysics
Geophysics and Gravity Measurements
1.79
article

Limb-darkening coefficients for four-term and power-2 laws for the JWST mission adopting spherical PHOENIX models at high resolution

Guillermo Torres, A. Claret, P. H. Hauschildt
article en
1 citations

Abstract

Aims. Modeling observations of transiting exoplanets or close binary systems by comparing the observations with theoretical light curves requires precise knowledge of the distribution of specific intensities across the stellar disk. We aim to facilitate this type of research by providing extensive tabulations of limb-darkening coefficients for 11 frequently used near- and mid-infrared passbands on the NIRCam, NIRISS, and NIRSpec instruments installed on board the James Webb Space Telescope. Methods. The calculation of the limb-darkening coefficients was based on spherically symmetric atmosphere models from the PHOENIX series, with a high spectral resolution (approximately 10 6 wavelengths), and covering the wavelength range 0.1-6.0 μ m. The models were computed for solar composition, and a microturbulent velocity of 1.0 kms -1 . We adopted two of the more accurate parametrizations for the coefficients: the four-term law, and the power-2 law. We applied the Levenberg-Marquardt least-squares minimization method, with a strategy to determine the critical value, μ crit , of the cosine of the viewing angle near the limb that is designed to improve numerical accuracy. Results. The limb-darkening coefficients were derived based on a total of 306 atmosphere models covering an effective temperature range of 2400-7800 K, and a log g interval between 3.0 and 5.5. We discuss the quality of the fits to the specific intensities provided by the power-2 and four-term laws, as well as by the often-used quadratic law. Based on a comparison, we recommend the use of the four-term or power-2 laws, in that order of preference.

Astronomy and AstrophysicsVol. 699
Universität Hamburg (DE), Universidad de Granada (ES), Center for Astrophysics Harvard & Smithsonian (US), Hamburger Fern-Hochschule (DE), Instituto de Astrofísica de Andalucía (ES)
U.S. Department of Energy, National Aeronautics and Space Administration, National Energy Research Scientific Computing Center, Bundesministerium für Bildung und Forschung, Instituto de Astrofísica de Andalucía, Office of Science, Agencia Estatal de Investigación
Openalex Percentile: Top 17%
Geophysics and Gravity Measurements
1.79
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