J/A+A/699/A97 Limb-darkening coefficients for JWST (Claret+, 2025)
Limb-darkening coefficients for the 4-term and power-2 laws for the JWST mission
adopting spherical PHOENIX models at high resolution.
NIRCam, NIRISS and NIRSpec passbands.
Claret, A., Hauschildt, P.H., Torres, G.
<Astron. Astrophys. 699, A97 (2025)>
=2025A&A...699A..97C 2025A&A...699A..97C (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, eclipsing ; Stars, double and multiple;
Models, atmosphere ; Photometry, infrared ; Spectra, infrared
Keywords: stars: atmospheres - binaries: eclipsing
Abstract:
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. The calculation of the limb-darkening coefficients
was based on spherically symmetric atmosphere models from the PHOENIX
series, with high spectral resolution (approximately one million
wavelengths), and covering the wavelength range 0.1-6.0 microns. The
models were computed for solar composition, and a microturbulent
velocity of 1.0km/s. We adopted two of the more accurate
parametrizations for the coefficients: the 4-term law, and the power-2
law. We applied the Levenberg-Marquardt least-squares minimization
method, with a strategy to determine the critical value mucrit of
the cosine of the viewing angle near the limb that is designed to
improve numerical accuracy. The limb-darkening coefficients were
derived based on a total of 306 atmosphere models covering an
effective temperature range of 2400-7800K, 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 4-term laws, as well
as by the often used quadratic law. Based on a comparison, we
recommend the use of the 4-term or power-2 laws, in that order of
preference.
Description:
The tables provide limb-darkening coefficients for 11 frequently used
near- and mid-infrared passbands on the NIRCam, NIRISS, and NIRSpec
instruments on board the James Webb Space Telescope. The calculations
are based on spherically symmetric atmosphere models from the PHOENIX
series, with high spectral resolution (using approximately 106
wavelengths) covering the wavelength range 0.1-6.0 microns. The 306
atmosphere models used cover an effective temperature range of
2400-7800K, and a logg interval between 3.0 and 5.5. The atmosphere
models were computed for solar composition and a microturbulent
velocity of 1km/s. The parametrizations used are the 4-term law (eq.
7) and the power-2 law (eq. 6), and the corresponding coefficients
were computed by least squares, fitting 60,000 regularly-spaced points
interpolated among the model intensities. The tables also provide the
critical values of mu for each filter (smallest cosine of the viewing
angle near the limb that is used for the fits), and the resulting
chi-squared value of the fit, which serves as an indicator of the
quality of the adjustment.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 82 3366 Limb-darkening coefficients for the 4-term law
table3.dat 62 3366 Limb-darkening coefficients for the power-2 law
(corrected version, 10-Jul-2025)
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See also:
J/A+AS/114/247 : Limb-darkening coefficients for R I J H K (Claret+, 1995)
J/A+A/335/647 : Limb-darkening coefficients for ubvyUBVRIJHK (Claret 1998)
J/A+A/401/657 : Non-linear limb-darkening law for LTE models. II.
(Claret, 2003)
J/A+A/428/1001 : Non-linear limb-darkening law for LTE models. III.
(Claret, 2004)
J/A+A/529/A75 : Limb-darkening coefficients (Claret+, 2011)
J/A+A/546/A14 : Limb-darkening for CoRoT, Kepler, Spitzer (Claret+, 2012)
J/A+A/552/A16 : Limb-darkening for CoRoT, Kepler, Spitzer. II. (Claret+, 2013)
J/A+A/600/A30 : Limb-darkening for TESS satellite (Claret, 2017)
J/A+A/618/A20 : Limb-darkening for TESS, Kepler, Corot, MOST (Claret, 2018)
J/A+A/634/A93 : Limb-darkening coefficients for compact stars (Claret+, 2020)
J/A+A/641/A157 : Limb-darkening coefficients for white dwarfs (Claret+, 2020)
J/A+A/674/A63 : Power-2 limb-darkening coefficients for JWST (Claret+, 2023)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 F4.2 [cm/s2] logg Log surface gravity
6- 9 I4 K Teff Effective temperature
11- 16 A6 --- Filter Name of filter (G1)
18- 27 F10.6 --- a1 Coefficient a1 of 4-term law (2)
29- 38 F10.6 --- a2 Coefficient a2 of 4-term law (2)
40- 49 F10.6 --- a3 Coefficient a3 of 4-term law (2)
51- 60 F10.6 --- a4 Coefficient a4 of 4-term law (2)
62- 71 F10.6 --- mucrit Critical value of mu
73- 82 F10.6 --- chi2 Chi-squared value (G3)
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Note (2): Follows eq. 7 in the paper, I(mu)/I(1)=1-∑(k=1,4)ak(1-muk/2).
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 F4.2 [cm/s2] logg Log surface gravity
6- 9 I4 K Teff Effective temperature
11- 16 A6 --- Filter Name of filter (G1)
18- 28 F11.6 --- g ? Coefficient g of power-2 law (2)
30- 40 F11.6 --- h Coefficient h of power-2 law (2)
42- 51 F10.6 --- mucrit Critical value of mu
53- 62 F10.6 --- chi2 Chi-squared value (G3)
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Note (2): Follows eq. 6 in the paper, I(mu)/I(mu=1)=1-g(1-muh).
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Global notes:
Note (G1): Instrument and passband, as listed in Table 1 of the paper,
as follows:
F210M = NIRCam F210M, lambda0=2.10um
F322W2 = NIRCam F322W2, lambda0=3.34um
F444W = NIRCam F444W, lambda0=4.44um
SOSS1 = NIRISS SOSS Order 1, lambda0=1.80um
SOSS2 = NIRISS SOSS Order 2, lambda0=0.80um
F277W = NIRISS F277W, lambda0=2.80um
G235H = NIRSpec G235H/F170LP, lambda0=2.44um
G235M = NIRSpec G235M/F170LP, lambda0=2.45um
G395H = NIRSpec G395H/F290LP, lambda0=4.04um
G395M = NIRSpec G395M/F290LP, lambda0=4.03um
PRISM = NIRSpec PRISM, lambda0=3.65um
Note (G3): Figure of merit defined in eq. 10 of the paper,
chi2={Sum}(i=1,N)(yi-Yi)2, where yi is the model intensity
at point i, Yi is the fitted function at the same point, and
N is the number of mu points.
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Acknowledgements:
Antonio Claret, claret(at)iaa.es
Guillermo Torres, gtorres(at)cfa.harvard.edu
History:
04-Jul-2025: on-line version
10-Jul-2025: corrected table3
(End) Antonio Claret [IAA], Patricia Vannier [CDS] 10-Jun-2025