J/AJ/163/228 Limb-darkening coefficients of 176 TESS exoplanets (Patel+, 2022)
Empirical Limb-darkening Coefficients and Transit Parameters of Known Exoplanets
from TESS.
Patel J.A., Espinoza N.
<Astron. J., 163, 228 (2022)>
=2022AJ....163..228P 2022AJ....163..228P
ADC_Keywords: Exoplanets; Optical
Keywords: Transit photometry ; Limb darkening ; Exoplanets
Abstract:
Although the main goal of the Transiting Exoplanet Survey Satellite
(TESS) is to search for new transiting exoplanets, its data can also
be used to study already-known systems in further detail. The TESS
bandpass is particularly interesting to study the limb-darkening
effect of the stellar host that is imprinted in transit light curves,
as the widely used phoenix and atlas stellar models predict different
limb-darkening profiles. Here we study this effect by fitting the
transit light curves of 176 known exoplanetary systems observed by
TESS, which allows us to extract empirical limb-darkening coefficients
(LDCs) for the widely used quadratic law but also updated transit
parameters (including ephemeride refinements) as a by-product.
Comparing our empirically obtained LDCs with theoretical predictions,
we find significant offsets when using tabulated TESS LDCs.
Specifically, the u2 coefficients obtained using phoenix models show
the largest discrepancies depending on the method used to derive them,
with offsets that can reach up to Δu2 ∼0.2, on average. Most of
those average offsets disappear, however, if one uses the SPAM
algorithm introduced by Howarth to calculate the LDCs instead. Our
results suggest, however, that for stars cooler than about 5000K, no
methodology is good enough to explain the limb-darkening effect; we
observe a sharp deviation between measured and predicted LDCs on both
quadratic LDCs of order Δu1, Δu2 ∼0.2 for those cool
stars. We recommend caution when assuming LDCs as perfectly known, in
particular for these cooler stars when analyzing TESS transit light
curves.
Description:
In this paper, our main goal was to study the limb-darkening of
exoplanet host stars using Transiting Exoplanet Survey Satellite
(TESS) transiting exoplanet light curves. To achieve this goal, we
used precise exoplanet transit light curves obtained by TESS for 176
known exoplanetary systems, for which we computed limb-darkening
coefficients (LDCs), the primary products needed to meet our goal.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 98 176 Various stellar properties of our targets
table4.dat 89 176 Limb darkening coefficients calculated using
different methods for quadratic law
table5.dat 68 176 SPAM limb darkening coefficients calculated using
different methods for quadratic law
table6.dat 191 176 Retrieved planetary parameters along with their
literature values
--------------------------------------------------------------------------------
See also:
J/A+A/363/1081 : Non-linear limb-darkening law for LTE models (Claret 2000)
J/ApJ/709/159 : Relative Ic photometry of WASP-17 (Anderson+, 2010)
J/A+A/527/A8 : Transiting planetary system WASP-7 (Southworth+, 2011)
J/A+A/546/A14 : Limb-darkening for CoRoT, Kepler, Spitzer (Claret+, 2012)
J/A+A/539/A102 : HD 209458 and HD 189733 theoretical spectra (Hayek+, 2012)
J/MNRAS/426/1291 : Physical properties of 38 exoplanets (Southworth, 2012)
J/MNRAS/436/2 : Transits of WASP-19b (Mancini+, 2013)
J/MNRAS/428/3671 : Transiting planet WASP-19b (Tregloan-Reed+, 2013)
J/A+A/564/A125 : AGN Torus model comparison of AGN in the CDFS (Buchner+, 2014)
J/AJ/152/127 : Sloan i follow-up light curves of HATS-18 (Penev+, 2016)
J/A+A/602/A107 : 231 transiting planets eccentricity and mass (Bonomo+, 2017)
J/A+A/600/A30 : Limb-darkening for TESS satellite (Claret, 2017)
J/MNRAS/465/3693 : 7 WASP-South transiting exoplanets (Hellier+, 2017)
J/AJ/154/228 : Properties of transiting planet's host stars (Sandford+, 2017)
J/AJ/153/136 : Planets & their host stars with Gaia plxs (Stassun+, 2017)
J/A+A/616/A39 : Power-2 limb-darkening law from STAGGER-grid (Maxted, 2018)
J/AJ/157/43 : WASP-161b, WASP-163b and WASP-170b (Barkaoui+, 2019)
J/AJ/157/217 : Transit times of 5 hot Jupiter WASP exoplanets (Bouma+, 2019)
J/A+A/635/A205 : Ultra-hot Jupiter WASP-121b transits (Bourrier+, 2020)
J/AJ/160/209 : K2 & TESS Synergy. I. Param & LC, 4 stars (Ikwut-Ukwa+, 2020)
J/AcA/70/181 : Search for Planets in Hot Jupiter Systems (Maciejewski+, 2020)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Name Name of the host star
10- 15 F6.1 K Teff [3036/8720] Effective temperature (1)
17- 22 F6.3 [-] Fe/H [-0.35/0.47]? Metallicity (1)
24- 28 F5.3 [cm/s2] logg [3.58/5.06] Surface gravity (1)
30- 32 A3 km/s Vt Turbulent velocity
34- 54 A21 --- r_Teff Reference bibcode to the effective temperature
56- 76 A21 --- r_Fe/H Reference bibcode to the metallicity (2)
78- 98 A21 --- r_logg Reference bibcode to the surface gravity
--------------------------------------------------------------------------------
Note (1): The data of literature planetary parameters was extracted from the
"Composite Planet Data Table" of the NASA Exoplanet Archive on
February 23, 2021.
Note (2): A null value means that the metallicity for the source was not
available. In this case, we put "NONE" in the reference column.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Name Name of the host star
10- 13 F4.2 --- u1-j [0.13/1.35] u1 determined from juliet analysis
15- 18 F4.2 --- u1-j-p [0.01/0.54] upper band of 68% credibility
20- 23 F4.2 --- u1-j-n [0.01/0.83] lower band of 68% credibility
25- 29 F5.2 --- u2-j [-0.41/0.57] u2 determined from juliet
analysis
31- 34 F4.2 --- u2-j-p [0.02/0.57] upper band of 68% credibility
36- 39 F4.2 --- u2-j-n [0.02/0.47] lower band of 68% credibility
41- 44 F4.2 --- u1-code-ata [0.14/0.54] u1 from EJ15 ATLAS
46- 49 F4.2 --- u2-code-ata [0.13/0.44] u2 from EJ15 ATLAS
51- 54 F4.2 --- u1-code-pho [0.12/0.5] u1 from EJ15 PHOENIX
56- 59 F4.2 --- u2-code-pho [0.17/0.56] u2 from EJ15 PHOENIX
61- 64 F4.2 --- u1-cla-ata [0/0.51] u1 from C17 ATLAS
66- 69 F4.2 --- u2-cla-ata [0/0.4] u2 from C17 ATLAS
71- 74 F4.2 --- u1-cla-pho [0.01/0.45] u1 from C17 PHOENIX
76- 79 F4.2 --- u2-cla-pho [0.26/0.72] u2 from C17 PHOENIX
81- 84 F4.2 --- u1-cla-pho-r [0.11/0.49] u1 from C17 PHOENIX, with r-method
86- 89 F4.2 --- u2-cla-pho-r [0.18/0.58] u2 from C17 PHOENIX, with r-method
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- Name Name of the host star
18- 21 F4.2 --- u1-code-ata [0.16/0.58] u1 from EJ15 ATLAS
23- 26 F4.2 --- u2-code-ata [0.06/0.47] u2 from EJ15 ATLAS
28- 31 F4.2 --- u1-code-pho [0.17/0.55] u1 from EJ15 PHOENIX
33- 36 F4.2 --- u2-code-pho [0.09/0.47] u2 from EJ15 PHOENIX
38- 42 F5.2 --- u1-cla-ata [-0.09/0.55] u1 from C17 ATLAS
44- 48 F5.2 --- u2-cla-ata [-0.01/0.5] u2 from C17 ATLAS
50- 53 F4.2 --- u1-cla-pho [0.16/0.54] u1 from C17 PHOENIX
55- 58 F4.2 --- u2-cla-pho [0.11/0.47] u2 from C17 PHOENIX
60- 63 F4.2 --- u1-cla-pho-r [0.16/0.54] u1 from C17 PHOENIX, with r-method
65- 68 F4.2 --- u2-cla-pho-r [0.10/0.47] u2 from C17 PHOENIX, with r-method
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Name of the planet
11- 16 F6.4 --- Rp/R* [0.02/0.23] Rp/R* retrieved from this work
18- 23 F6.4 --- Rp/R*-u [0/0.03] Upper 68% credibility band on Rp/R*
25- 30 F6.4 --- Rp/R*-l [0/0.03] Lower 68% credibility band on Rp/R*
32- 36 F5.2 --- a/R* [3.42/39.6] a/R* retrieved from this work
38- 41 F4.2 --- a/R*-u [0.01/4.68] Upper 68% credibility band on a/R*
43- 46 F4.2 --- a/R*-l [0.01/7.84] Lower 68% credibility band on a/R*
48- 57 F10.5 d T0 [332/1254] Transit time (BJD-2458000) from
this work
59- 65 F7.5 d T0-u [0/0.06] Upper 68% credibility band on transit
time
67- 73 F7.5 d T0-l [0/0.06] Lower 68% credibility band on transit
time
75- 80 F6.4 --- rprst [0/0.24] Literature value of Rp/R* (1)
82- 87 F6.4 --- rprst-u [0/0.1] Upper 68% credibility on Rp/R* from
literature (1)
89- 94 F6.4 --- rprst-l [0/0.1] Lower 68% credibility on Rp/R* from
literature (1)
96-100 F5.2 --- aste [3.46/38.7] Literature value of a/R* (1)
102-105 F4.2 --- aste-u [0/2.9] Upper 68% credibility band on literature
value of a/R* (1)
107-110 F4.2 --- aste-l [0/2.9] Lower 68% credibility band on literature
value of a/R* (1)
112-119 F8.3 d T0-lit [332/1254] Transit time (BJD-2458000) predicted
from literature (1)
121-125 F5.3 d e_T0-lit [0/0.19] 1-sigma errors on predicted transit
time (1)
127-147 A21 --- r_Rp/R* Reference bibcode for literature value of Rp/R*
149-169 A21 --- r_a/R* Reference bibcode for literature value of a/R*
171-191 A21 --- r_T0 Reference bibcode for literature value of
transit time
--------------------------------------------------------------------------------
Note (1): The data of literature planetary parameters was extracted from the
"Composite Planet Data Table" [doi:10.26133/NEA2] of the NASA Exoplanet
Archive on February 23, 2021.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 16-Sep-2022