J/AJ/161/174 Transit depth biases & error bars for 31 planets (Morello+, 2021)
Phase-curve pollution of exoplanet transmission spectra.
Morello G., Zingales T., Martin-Lagarde M., Gastaud R., Lagage P.-O.
<Astron. J., 161, 174 (2021)>
=2021AJ....161..174M 2021AJ....161..174M
ADC_Keywords: Exoplanets; Spectra, infrared
Keywords: Exoplanet atmospheres ; Transmission spectroscopy ;
Exoplanet systems ; Exoplanets ; Infrared observatories
Abstract:
The occurrence of a planet transiting in front of its host star offers
the opportunity to observe the planet's atmosphere filtering
starlight. The fraction of occulted stellar flux is roughly
proportional to the optically thick area of the planet, the extent of
which depends on the opacity of the planet's gaseous envelope at the
observed wavelengths. Chemical species, haze, and clouds are now
routinely detected in exoplanet atmospheres through rather small
features in transmission spectra, i.e., collections of planet-to-star
area ratios across multiple spectral bins and/or photometric bands.
Technological advances have led to a shrinking of the error bars down
to a few tens of parts per million (ppm) per spectral point for the
brightest targets. The upcoming James Webb Space Telescope (JWST) is
anticipated to deliver transmission spectra with precision down to
10ppm. The increasing precision of measurements requires a
reassessment of the approximations hitherto adopted in astrophysical
models, including transit light-curve models. Recently, it has been
shown that neglecting the planet's thermal emission can introduce
significant biases in the transit depth measured with the
JWST/Mid-InfraRed Instrument, integrated between 5 and 12µm. In
this paper, we take a step forward by analyzing the effects of the
approximation on transmission spectra over the 0.6-12µm wavelength
range covered by various JWST instruments. We present open-source
software to predict the spectral bias, showing that, if not corrected,
it may affect the inferred molecular abundances and thermal structure
of some exoplanet atmospheres.
Description:
We obtained the transmission spectra associated with three James Webb
Space Telescope (JWST) instruments using the observing modes as
follows:
1. The Near-InfraRed Imager and Slitless Spectrograph (NIRISS) with
the Single-Object Slitless Spectroscopy (SOSS) mode (0.6-2.8µm)
2. The Near-InfraRed Spectrograph (NIRSpec) with the G235H and G395H
gratings (1.66-317 and 2.87-5.27µm respectively)
3. the Mid-InfraRed Instrument (MIRI) with the Low-Resolution
Spectroscopy (LRS) slitless mode (5-12µm).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 65 48 Transit depth biases and error bars estimated for
the most likely configurations
table5.dat 112 93 Transit depth biases and error bars estimated for
extreme configurations
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/A+A/531/A40 : Transits of WASP-39b (Faedi+, 2011)
J/A+A/549/A10 : Transits of GJ 1214 (Harpsoe+, 2013)
J/A+A/549/A134 : 4 new WASP transiting close-in giant planets (Hebrard+, 2013)
J/ApJ/790/53 : Photometric data of HD 209458b (Zellem+, 2014)
J/A+A/602/A107 : 231 transiting planets eccentricity and mass (Bonomo+, 2017)
J/A+A/600/L11 : GTC transit light curves of WASP-52b (Chen+, 2017)
J/A+A/599/A3 : WASP 127, 136 and 138 RV and light curves (Lam+, 2017)
J/A+A/616/A145 : GTC transit light curves of WASP-127b (Chen+, 2018)
J/A+A/625/A136 : WASP-18b HST/WFC3 spectroscopic phase curves (Arcangeli+,2019)
J/A+A/628/A39 : Radial velocities of GJ 357 (Luque+, 2019)
J/MNRAS/485/5168 : Light curves of WASP-74 (Mancini+, 2019)
J/AJ/158/243 : A search for multiplanet systems with TESS (Pearson, 2019)
J/A+A/640/A112 : TRAPPIST-1 transit timings (Ducrot+, 2020)
J/A+A/642/A50 : WASP-74 grizs light curves (Luque+, 2020)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Planet Planet identifier
12- 18 A7 --- Inst Instrument
20- 28 E9.2 ppm TB-Off Total most likely bias offset (1)
30 A1 ppm f_TB-Off [b] Flag on TB-Off (2)
32- 39 E8.2 ppm TB-Amp Total most likely bias amplitude (3)
41 A1 ppm f_TB-Amp [b] Flag on TB-Amp (2)
43- 51 E9.2 ppm SB-Off Self-blend most likely bias offset (1)
53- 60 E8.2 ppm SB-Amp Self-blend most likely bias amplitude (3)
62- 65 I4 ppm Error [7/143] Error bar
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Note (1): The offset is the mean value of the bias over the wavelength bins.
Note (2): Flag as follows:
b = bias values greater than 3X the nominal error bar and greater than 30ppm
Note (3): The amplitude is the difference between the maximum and minimum
bias over the wavelength bins.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Planet Planet identifier
14- 20 A7 --- Inst Instrument
22- 29 E8.2 ppm TB-Off+ Total positive extreme bias offset (1)
31 A1 --- f_TB-Off+ [b] Flag on TB-Off+ (2)
33- 41 E9.2 ppm TB-Off- Total negative extreme bias offset (1)
43 A1 --- f_TB-Off- [b] Flag on TB-Off- (2)
45- 52 E8.2 ppm TB-Amp+ Total positive extreme bias amplitude (3)
54 A1 --- f_TB-Amp+ [b] Flag on TB-Amp+ (2)
56- 63 E8.2 ppm TB-Amp- Total negative extreme bias amplitude (3)
65 A1 --- f_TB-Amp- [b] Flag on TB-Amp- (2)
67- 75 E9.2 ppm SB-Off+ Self-blend positive extreme bias offset (1)
77- 85 E9.2 ppm SB-Off- Self-blend negative extreme bias offset (1)
87 A1 --- f_SB-Off- [b] Flag on SB-Off- (2)
89- 96 E8.2 ppm SB-Amp+ Self-blend positive extreme bias amplitude (3)
98-105 E8.2 ppm SB-Amp- Self-blend negative extreme bias amplitude (3)
107 A1 --- f_SB-Amp- [b] Flag on SB-Amp- (2)
109-112 I4 ppm Error [7/299] Error Bar
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Note (1): The offset is the mean value of the bias over the wavelength bins.
Note (2): Flag as follows:
b = bias values greater than 3X the nominal error bar and greater than 30ppm
Note (3): The amplitude is the difference between the maximum and minimum
bias over the wavelength bins.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 30-Jul-2021