J/A+A/618/A20 Limb-darkening for TESS, Kepler, Corot, MOST (Claret, 2018)
A new method to compute limb-darkening coefficients for stellar atmosphere
models with spherical symmetry: the space missions TESS, Kepler, Corot, and
MOST.
Claret A.
<Astron. Astrophys. 618, A20 (2018)>
=2018A&A...618A..20C 2018A&A...618A..20C (SIMBAD/NED BibCode)
ADC_Keywords: Models, atmosphere ; Photometry
Keywords: binaries: eclipsing - stars: atmospheres - planetary systems
Abstract:
One of the biggest problems we can encounter while dealing with the
limb-darkening coefficients for stellar atmospheric models with
spherical symmetry is the difficulty of adjusting both the limb and
the central parts simultaneously. In particular, the regions near the
drop-offs are not well reproduced for most models, depending on Teff,
log g, or wavelength. Even if the law with four terms is used, these
disagreements still persist. Here we introduce a new method that
considerably improves the description of both the limb and the central
parts and that will allow users to test models of stellar atmospheres
with spherical symmetry more accurately in environments such as
exoplanetary transits, eclipsing binaries, etc.
Description:
The method introduced here is simple. Instead of considering all the
µ points in the adjustment, as is traditional, we consider only
the points until the drop-off (µ_cri-) of each model. From this
point, we impose a condition I(µ)/I(1)=0. All calculations were
performed by adopting the least-squares method.
The resulting coefficients using this new method reproduce the
intensity distribution of the PHOENIX spherical models (COND and
DRIFT) quite well for the photometric systems of the space missions
TESS, KEPLER, COROT, and MOST. The calculations cover the following
ranges of local gravity and effective temperatures: 2.5≤logg≤6.0 and
1500K≤Teff≤12000K. The new spherical coefficients can easily be
adapted to the most commonly used light curve synthesis codes.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 87 112 a1,a2,a3,a4 LDCs, FSM, Eq. 1
PHOENIX-DRIFT models, solar metallicity,
v.tu=2 km/s for TESS
table3.dat 87 574 a1,a2,a3,a4 LDCs, FSM, Eq. 1
PHOENIX-COND models, solar metallicity,
v.tu=2 km/s for TESS
table4.dat 68 112 a,b quadratic LDCs, FSM, Eq. 2
PHOENIX-DRIFT models, solar metallicity,
v.tu=2 km/s for TESS
table5.dat 68 574 a,b quadratic LDCs, FSM, Eq. 2
PHOENIX-COND models, solar metallicity,
v.tu=2 km/s for TESS
table6.dat 87 112 a1,a2,a3,a4 LDCs, FSM, Eq. 1
PHOENIX-DRIFT models, solar metallicity,
v.tu=2 km/s for KEPLER
table7.dat 87 574 a1,a2,a3,a4 LDCs, FSM, Eq. 1
PHOENIX-COND models, solar metallicity,
v.tu=2 km/s for KEPLER
table8.dat 68 112 a,b quadratic LDCs, FSM, Eq. 2
PHOENIX-DRIFT models, solar metallicity,
v.tu=2 km/s for KEPLER
table9.dat 68 574 a,b quadratic LDCs, FSM, Eq. 2
PHOENIX-COND models, solar metallicity,
v.tu=2 km/s for KEPLER
table10.dat 87 112 a1,a2,a3,a4 LDCs, FSM, Eq. 1
PHOENIX-DRIFT models, solar metallicity,
v.tu=2 km/s for COROT
table11.dat 87 574 a1,a2,a3,a4 LDCs, FSM, Eq. 1
PHOENIX-COND models, solar metallicity,
v.tu=2 km/s for COROT
table12.dat 68 112 a,b quadratic LDCs, FSM, Eq. 2
PHOENIX-DRIFT models, solar metallicity,
v.tu=2 km/s for COROT
table13.dat 68 574 a,b quadratic LDCs, FSM, Eq. 2
PHOENIX-COND models, solar metallicity,
v.tu=2 km/s for COROT
table14.dat 87 112 a1,a2,a3,a4 LDCs, FSM, Eq. 1
PHOENIX-DRIFT models, solar metallicity,
v.tu=2 km/s for MOST
table15.dat 87 574 a1,a2,a3,a4 LDCs, FSM, Eq. 1
PHOENIX-COND models, solar metallicity,
v.tu=2 km/s for MOST
table16.dat 68 112 a,b quadratic LDCs, FSM, Eq. 2
PHOENIX-DRIFT models, solar metallicity,
v.tu=2 km/s for MOST
table17.dat 68 574 a,b quadratic LDCs, FSM, Eq. 2
PHOENIX-COND models, solar metallicity,
v.tu=2 km/s for MOST
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See also:
J/A+A/363/1081 : Non-linear limb-darkening law for LTE models (Claret, 2000)
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/600/A30 : Limb-darkening for TESS satellite (Claret, 2017)
Byte-by-byte Description of file: table[2367].dat table1[0145].dat
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Bytes Format Units Label Explanations
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1- 5 F5.2 cm/s+2 logg [2.5/6.0] Surface gravity
7- 12 F6.0 K Teff [1500/12000] Effective temperature
14- 17 F4.1 [-] Z [0] Metallicity (log[M/H])
19- 22 F4.1 --- L/HP [2] Mixing-length parameter
24- 31 F8.4 --- a1 Eq. 1 spherical linear limb darkening coefficient
a1 (FSM) (1)
33- 41 F9.4 --- a2 Eq. 1 spherical linear limb darkening coefficient
a2 (FSM) (1)
43- 50 F8.4 --- a3 Eq. 1 spherical linear limb darkening coefficient
a3 (FSM) (1)
52- 59 F8.4 --- a4 Eq. 1 spherical linear limb darkening coefficient
a4 (FSM) (1)
61- 68 F8.4 --- mu MUCRI parameter (FSM)
70- 77 F8.4 --- chi2 SQRT(CHI2Q) (FSM)
79- 80 A2 --- Mod [PD PC] Model name (G1)
82- 87 A6 --- Sys System (TESS, KEPLER, COROT or MOST)
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Note (1): Eq. 1 : Non-linear law
I(µ)/I(1) = 1 - a1*(1-µ0.5) - a2*(1-µ)
- a3*(1-µ1.5) - a4*(1-µ2)
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Byte-by-byte Description of file: table[4589].dat table1[2367].dat
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Bytes Format Units Label Explanations
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1- 5 F5.2 cm/s+2 logg [2.5/6.0] Surface gravity
7- 12 F6.0 K Teff [1500/12000] Effective temperature
14- 17 F4.1 [-] Z [0] Metallicity (log[M/H])
19- 22 F4.1 --- L/HP [2] Mixing-length parameter
24- 31 F8.4 --- a Eq.2 spherical linear limb darkening coefficient
a (FSM) (2)
33- 40 F8.4 --- b Eq.2 spherical linear limb darkening coefficient
b (FSM) (2)
42- 49 F8.4 --- mu MUCRI parameter (FSM)
51- 58 F8.4 --- chi2 SQRT(CHI2Q) (FSM)
60- 61 A2 --- Mod [PD PC] Model name (G1)
63- 68 A6 --- Sys System (TESS, KEPLER, COROT or MOST)
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Note (2): Eq. 2 : Quadratic law I(µ)/I(1) = 1-a(1-µ)-b(1-µ)2
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Global notes:
Note (G1): Models as follows:
PD = PHOENIX-DRIFT
PC = PHOENIX-COND
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Acknowledgements:
Antonio Claret, claret(at)iaa.es
(End) Patricia Vannier [CDS] 17-May-2018