ExoTiC-ISM: A Python package for marginalised exoplanet transit parameters across a grid of systematic instrument models

Laginja, Iva; Wakeford, Hannah R.

doi:10.21105/joss.02281

Cited by 15 publications

(18 citation statements)

References 20 publications

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“…For the analytic transit light curve model, we use batman [34] with a quadratic limb darkening law. We use ExoTiC-LD [55][56][57], with 3D stellar models [38] to determine the appropriate coefficients, adopting the stellar parameters (T eff = 5512 ± 55 K, log g = 4.47 ± 0.03 cgs, [Fe/H] = 0.01 ± 0.09 dex) from [43] and Gaia DR3 [58,59]. For our final fits, we fix the quadratic coefficient, u 2 , to the values determined by ExoTiC-LD.…”

Section: Tiberiusmentioning

confidence: 99%

“…[48] (https://eurekadocs.readthedocs.io/en/latest/), and Tiberius [16,53,54] . In addition, these made use of Exoplanet [45] (https://docs.exoplanet.codes/en/latest/), Pymc3 [79] (https://docs.pymc.io/en/v3/index.html), ExoTEP [49−−51] , Batman [34] (http://lkreidberg.github.io/batman/docs/html/index.html), ExoTiC-ISM [55] (https://github.com/Exo-TiC/ExoTiC-ISM), ExoTiC-LD [57] (https://exotic-ld.readthedocs.io/en/latest/), Emcee [33] (https://emcee.readthedocs.io/en/stable/), Dynesty [71] (https://dynesty.readthedocs.io/en/stable/index.html), and chromatic (https://zkbt.github.io/chromatic/), which use the python libraries scipy [80] , numpy [81] , astropy [82,83] , and matplotlib [84] . The atmospheric models used to fit the data can be found at PICASO [62−−65] (https://natashabatalha.github.io/picaso/), Virga85 (https://natashabatalha.github.io/virga/), ScCHIMERA [60,61] (https://github.com/mrline/CHIMERA), ATMO [67,68] , and PHOENIX [69,70].…”

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confidence: 99%

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WITHDRAWN: The Broadband Transmission Spectrum of WASP-39b from JWST NIRSpec PRISM Observations

Rustamkulov

Sing

Line

et al. 2022

Preprint

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Transmission spectroscopy of exoplanets has revealed signatures of water vapor, aerosols, and alkali metals in a few dozen exoplanet atmospheres. However, these previous inferences with the Hubble and Spitzer Space Telescopes were hindered by the observations’ relatively narrow wavelength range and spectral resolving power, which precluded the unambiguous identification of other chemical species—in particular the primary carbon-bearing molecules. Here we report a broad-wavelength 0.5–5.5 μm atmospheric transmission spectrum of WASP-39 b, a 1200 K, roughly Saturn-mass, Jupiter-radius exoplanet, measured with JWST NIRSpec’s PRISM mode as part of the JWST Transiting Exoplanet Community Early Release Science Team program. We robustly detect multiple chemical species at high significance, including Na (19σ), H2O (33σ), CO2 (28σ), and CO (7σ). The non-detection of CH4, combined with a strong CO2 feature, favours atmospheric models with a super-Solar atmospheric metallicity. An unanticipated absorption feature at 4μm is best explained by SO2 (2.7σ), which could be a tracer of atmospheric photochemistry. These observations demonstrate JWST’s sensitivity to a rich diversity of exoplanet compositions and chemical processes.

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Section: Tiberiusmentioning

confidence: 99%

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confidence: 99%

WITHDRAWN: The Broadband Transmission Spectrum of WASP-39b from JWST NIRSpec PRISM Observations

Rustamkulov

Sing

Line

et al. 2022

Preprint

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“…For the analytic transit light curve model, we use batman 33 with a quadratic limb darkening law. We use ExoTiC-LD 55,56 , with 3D stellar models 39 to determine the appropriate coefficients, adopting the stellar parameters (T eff = 5512±55K, logg = 4.47±0.03 cgs, [Fe/H] = 0.01±0.09 dex) from 34 and Gaia DR3 57,58 . For our final fits, we fix the quadratic coefficient, u 2 , to the values determined by ExoTiC-LD.…”

Section: Tiberiusmentioning

confidence: 99%

Early Release Science of the exoplanet WASP-39b with JWST NIRSpec PRISM

Rustamkulov

Sing

Mukherjee

et al. 2023

Nature

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132

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Transmission spectroscopy 1,2,3 of exoplanets has revealed signatures of water vapor, aerosols, and alkali metals in a few dozen exoplanet atmospheres 4,5 . However, these previous inferences with the Hubble and Spitzer Space Telescopes were hindered by the observations' relatively narrow wavelength range and spectral resolving power, which precluded the unambiguous identification of other chemical species -in particular the primary carbon-bearing molecules 6,7 . Here we report a broad-wavelength 0.5-5.5 µm atmospheric transmission spectrum of WASP39 b 8 , a 1200 K, roughly Saturn-mass, Jupiter-radius exoplanet, measured with JWST NIRSpec's PRISM mode 9 as part of the JWST Transiting Exoplanet Community Early Release Science Team program 10,11,12 . We robustly detect multiple chemical species at high significance, including Na (19σ), H 2 O (33σ), CO 2 (28σ), and CO (7σ). The non-detection of CH 4 , combined with a strong CO 2 feature, favours atmospheric models with a super-solar atmospheric metallicity. An unanticipated absorption feature at 4µm is best explained by SO 2 (2.7σ), which could be a tracer of atmospheric photochemistry. These observations demonstrate JWST's sensitivity to a rich diversity of exoplanet compositions and chemical processes.We observed one transit of WASP-39b on 10 July 2022 with JWST's Near InfraRed Spectrograph (NIRSpec) 9,13 , using the PRISM mode, as part of the JWST Transiting Exoplanet Community Early Release Science Program (ERS Program 1366) (PIs: N. Batalha, J. Bean, K. Stevenson) 10,11 . These observations cover the 0.5-5.5µm wavelength range at a native resolving power of R = λ/∆λ ∼ 20-300. WASP-39b was selected for this JWST ERS Program due to previous space-and ground-based observations revealing strong alkali metal absorption and multiple prominent H 2 O bands 4,6,14,15,16 , suggesting strong signal-to-noise could be obtained with JWST. However, the limited wavelength range of existing transmission spectra (0.3-1.65µm, combined with two wide photometric Spitzer channels at 3.6 and 4.5µm) left several important questions unresolved. Previous estimates of WASP-39b's atmospheric metallicity-a measure of the relative abundance of all gases heavier than hydrogen or helium-vary by four orders of magnitude 6,16,17,18,19,20 . Accurate determinations of metallicity can elucidate formation pathways and provide greater insight into the planet's history 21 . The JWST NIRSpec PRISM observations we present here offer a more detailed view into WASP-39b's atmospheric composition than has previously been possible (see ref. 21 for an initial infrared analysis of this data).We obtained time-series spectroscopy over 8.23 hours centered around the transit event to extract the wavelength-dependent absorption by the planet's atmosphere-i.e., the transmission spectrum, which probes the planet's day-night terminator region near millibar pressures. We used NIRSpec PRISM in Bright Object Time Series (BOTS) mode. WASP-39 is a bright, nearby, relatively inactive 23 G7 type star with an effective tempe...

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“…To fit the HST light curves and correct them for systematic effects from the telescope and instruments, we use the systematic instrument marginalisation method outlined in Wakeford et al (2016). For our WFC3/G102 and G141 light curves, we use the ExoTiC-ISM python package developed by Laginja & Wakeford (2020). ExoTiC-ISM uses a Levenberg-Marquardt least-squares minimisation over a grid of 50 systematic models 5 to obtain a set of fitted transit parameters for each model, making use of the resulting Akaike Information Criterion (AIC, Akaike 1974) to calculate each model's evidence and weight.…”

Section: Hubblementioning

confidence: 99%

“…This analysis made use of components of the IDL Astronomy Users Library (Landsman 1995) and the Python packages: NumPy (Oliphant 2006), SciPy (Virtanen et al 2019), MatPlotLib (Caswell et al 2019) (Buchner et al 2014b). This research made use of ExoTiC-ISM (Laginja & Wakeford 2020), a software package for marginalised transit parameters, which was developed based on the work by Wakeford et al (2016).…”

Section: Acknowledgementsmentioning

confidence: 99%

A Comprehensive Analysis of WASP-17b's Transmission Spectrum from Space-Based Observations

Alderson,

Wakeford,

MacDonald

et al. 2022

Preprint

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Due to its 1770 𝐾 equilibrium temperature, WASP-17b, a 1.99 𝑅 Jup , 0.486 𝑀 Jup exoplanet, sits at the critical juncture between hot and ultra-hot Jupiters. We present its 0.3-5 𝜇m transmission spectrum, with newly obtained with Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) measurements, and, taking advantage of improved analysis techniques, reanalysed HST Space Telescope Imaging Spectrograph (STIS) and Spitzer Space Telescope Infrared Array Camera (IRAC) observations. We achieve a median precision of 132 ppm with a mean of 272 ppm across the whole spectrum. We additionally make use of Transiting Exoplanet Survey Satellite (TESS) and ground-based transit observations to refine the orbital period of WASP-17b. To interpret the observed atmosphere, we make use of free and equilibrium chemistry retrievals using the POSEIDON and ATMO retrieval codes respectively. We detect absorption due to H 2 O at > 7𝜎, and find evidence of absorption due to CO 2 at > 3𝜎. We see no evidence of previously detected Na and K absorption. Across an extensive suite of retrieval configurations, we find the data favours a bimodal solution with high or low metallicity modes, as a result of poor constraints in the optical and demonstrate the importance of using multiple statistics for model selection. Future James Webb Space Telescope (JWST) GTO observations, combined with the presented transmission spectrum, will enable precise constraints on WASP-17b's atmosphere.

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ExoTiC-ISM: A Python package for marginalised exoplanet transit parameters across a grid of systematic instrument models

Cited by 15 publications

References 20 publications

WITHDRAWN: The Broadband Transmission Spectrum of WASP-39b from JWST NIRSpec PRISM Observations

WITHDRAWN: The Broadband Transmission Spectrum of WASP-39b from JWST NIRSpec PRISM Observations

Early Release Science of the exoplanet WASP-39b with JWST NIRSpec PRISM

A Comprehensive Analysis of WASP-17b's Transmission Spectrum from Space-Based Observations

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