Retrieval Survey of Metals in Six Ultrahot Jupiters: Trends in Chemistry, Rain-out, Ionization, and Atmospheric Dynamics

Gandhi, Siddharth; Kesseli, Aurora Y.; Zhang, Y.; Louca, Amy; Snellen, I. A. G.; Brogi, Matteo; Miguel, Yamila; Casasayas-Barris, N.; Pelletier, Sonia; Landman, Rico; Maguire, C.; Gibson, Neale P.

doi:10.3847/1538-3881/accd65

“…There is a strong interdependence between species, common from previous observations of such targets (e.g., Line et al 2015;Burningham et al 2017;Piette & Madhusudhan 2020). This highlights that the absolute abundances of each species may not be as well constrained, but we find that their ratios are significantly more precise and robust, as also seen with ground-based high-resolution spectroscopy (Gibson et al 2022;Gandhi et al 2023;Pelletier et al 2023). The less prominent isotopologues, C 18 O and C 17 O, show the weakest correlation given their lower abundances.…”

Section: Co Isotopologuessupporting

confidence: 72%

“…We perform our atmospheric retrieval with HyDRA (Gandhi & Madhusudhan 2018;Gandhi et al 2023), modified to allow for the characterization of nonirradiated exoplanets, as discussed below. We use the JWST NIRSpec IFU G395H/ F290LP data set of VHS 1256 b (Miles et al 2023), covering the ∼4.1-5.3 μm wavelength range of NRS2.…”

Section: Atmospheric Retrievalmentioning

confidence: 99%

JWST Measurements of ¹³C, ¹⁸O, and ¹⁷O in the Atmosphere of Super-Jupiter VHS 1256 b

Gandhi,

de Regt,

Snellen

et al. 2023

ApJL

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Isotope ratios have recently been measured in the atmospheres of directly imaged and transiting exoplanets from ground-based observations. The arrival of JWST allows us to characterize exoplanetary atmospheres in further detail and opens up wavelengths inaccessible from the ground. In this work we constrain the carbon and oxygen isotopes 13C, 18O, and 17O from CO in the atmosphere of the directly imaged companion VHS 1256 b through retrievals of the ∼4.1–5.3 μm NIRSpec G395H/F290LP observations from the early-release science program (ERS 1386). We detect and constrain 13C16O, 12C18O, and 12C17O at 32σ, 16σ, and 10σ confidence respectively, thanks to the very high signal-to-noise observations. We find the ratio of abundances are more precisely constrained than their absolute values, with 12 C / 13 C = 62 − 2 + 2 , in between previous measurements for companions (∼30) and isolated brown dwarfs (∼100). The oxygen isotope ratios are 16 O / 18 O = 425 − 28 + 33 and 16 O / 17 O = 1010 − 100 + 120 . All of the ratios are lower than the local interstellar medium and solar system, suggesting that abundances of the more minor isotopes are enhanced compared to the primary. This could be driven by isotope fractionation in protoplanetary disks, which can potentially alter the carbon and oxygen ratios through isotope selective photodissociation, gas/ice partitioning, and isotopic exchange reactions. In addition to CO, we constrain 1H 2 16 O and 12C16O2 (the primary isotopologues of both species), but find only upper limits on 12C1H4 and 14N1H3. This work highlights the power of JWST to constrain isotopes in exoplanet atmospheres, with great promise in determining formation histories in the future.

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“…Phase curves are complex, but extremely informative observational diagnostics. They are currently one of the very few observational constraints that allow us to study the spatial inhomogeneities of exoplanets' atmosphere (examples of other methods can be found in Ehrenreich et al 2020;Gandhi et al 2023;Falco et al 2022;Pluriel et al 2022;Zingales et al 2022). In the Spitzer IRAC 1 and IRAC 2 bandpasses, where we expect the reflected light to be negligible, phase curves are a measure of the longitudinal temperature map (e.g.…”

Section: Pc Modellingmentioning

confidence: 99%

Asymmetry in the atmosphere of the ultra-hot Jupiter WASP-76 b

Demangeon,

Cubillos,

Singh

et al. 2024

A&A

4

0

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Context. WASP-76 b has been a recurrent subject of study since the detection of a signature in high-resolution transit spectroscopy data indicating an asymmetry between the two limbs of the planet. The existence of this asymmetric signature has been confirmed by multiple studies, but its physical origin is still under debate. In addition, it contrasts with the absence of asymmetry reported in the infrared (IR) phase curve. Aims. We provide a more comprehensive dataset of WASP-76 b with the goal of drawing a complete view of the physical processes at work in this atmosphere. In particular, we attempt to reconcile visible high-resolution transit spectroscopy data and IR broadband phase curves. Methods. We gathered 3 phase curves, 20 occultations, and 6 transits for WASP-76 b in the visible with the CHEOPS space telescope. We also report the analysis of three unpublished sectors observed by the TESS space telescope (also in the visible), which represents 34 phase curves. Results. WASP-76 b displays an occultation of 260 ± 11 and 152 ± 10 ppm in TESS and CHEOPS bandpasses respectively. Depending on the composition assumed for the atmosphere and the data reduction used for the IR data, we derived geometric albedo estimates that range from 0.05 ± 0.023 to 0.146 ± 0.013 and from <0.13 to 0.189 ± 0.017 in the CHEOPS and TESS bandpasses, respectively. As expected from the IR phase curves, a low-order model of the phase curves does not yield any detectable asymmetry in the visible either. However, an empirical model allowing for sharper phase curve variations offers a hint of a flux excess before the occultation, with an amplitude of ~40 ppm, an orbital offset of ~ −30°, and a width of ~20º. We also constrained the orbital eccentricity of WASP-76 b to a value lower than 0.0067, with a 99.7% confidence level. This result contradicts earlier proposed scenarios aimed at explaining the asymmetry observed in high-resolution transit spectroscopy. Conclusions. In light of these findings, we hypothesise that WASP-76 b could have night-side clouds that extend predominantly towards its eastern limb. At this limb, the clouds would be associated with spherical droplets or spherically shaped aerosols of an unknown species, which would be responsible for a glory effect in the visible phase curves.

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“…HRCCS leverages the planetary signal's Doppler shift due to its orbital motion to disentangle the planetary atmospheric emission or transmission lines from telluric and stellar lines. HRCCS has been used to detect several C-and O-bearing species (e.g., Birkby et al 2013;de Kok et al 2013;Hawker et al 2018) in addition to numerous refractory metals (e.g., Hoeijmakers et al 2019;Gandhi et al 2023;Pelletier et al 2023) in hot and ultrahot Jupiters. HRCCS also provides probes of atmospheric dynamics and has been used to measure wind and rotation speeds (Snellen et al 2010;Brogi et al 2016;Gandhi et al 2022).…”

Section: Introductionmentioning

confidence: 99%

A Combined Ground-based and JWST Atmospheric Retrieval Analysis: Both IGRINS and NIRSpec Agree that the Atmosphere of WASP-77A b Is Metal-poor

Smith,

Line,

Bean

et al. 2024

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Ground-based high-resolution and space-based low-resolution spectroscopy are the two main avenues through which transiting exoplanet atmospheres are studied. Both methods provide unique strengths and shortcomings, and combining the two can be a powerful probe into an exoplanet’s atmosphere. Within a joint atmospheric retrieval framework, we combined JWST NIRSpec/G395H secondary eclipse spectra and Gemini South/IGRINS pre- and post-eclipse thermal emission observations of the hot Jupiter WASP-77A b. Our inferences from the IGRINS and NIRSpec data sets are consistent with each other, and combining the two allows us to measure the gas abundances of H2O and CO, as well as the vertical thermal structure, with higher precision than either data set provided individually. We confirm WASP-77A b’s subsolar metallicity ([(C+O)/H] = −0.61 − 0.09 + 0.10 ) and solar C/O ratio (C/O = 0.57 − 0.06 + 0.06 ) . The two types of data are complementary, and our abundance inferences are mostly driven by the IGRINS data, while inference of the thermal structure is driven by the NIRSpec data. Our ability to draw inferences from the post-eclipse IGRINS data is highly sensitive to the number of singular values removed in the detrending process, potentially due to high and variable humidity. We also search for signatures for atmospheric dynamics in the IGRINS data and find that propagated ephemeris error can manifest as either an orbital eccentricity or a strong equatorial jet. Neither are detected when using more up-to-date ephemerides. However, we find moderate evidence of thermal inhomogeneity and measure a cooler nightside that presents itself in the later phases after secondary eclipse.

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Retrieval Survey of Metals in Six Ultrahot Jupiters: Trends in Chemistry, Rain-out, Ionization, and Atmospheric Dynamics

Cited by 33 publications

References 118 publications

JWST Measurements of ¹³C, ¹⁸O, and ¹⁷O in the Atmosphere of Super-Jupiter VHS 1256 b

JWST Measurements of ¹³C, ¹⁸O, and ¹⁷O in the Atmosphere of Super-Jupiter VHS 1256 b

Asymmetry in the atmosphere of the ultra-hot Jupiter WASP-76 b

A Combined Ground-based and JWST Atmospheric Retrieval Analysis: Both IGRINS and NIRSpec Agree that the Atmosphere of WASP-77A b Is Metal-poor

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Retrieval Survey of Metals in Six Ultrahot Jupiters: Trends in Chemistry, Rain-out, Ionization, and Atmospheric Dynamics

Cited by 33 publications

References 118 publications

JWST Measurements of 13C, 18O, and 17O in the Atmosphere of Super-Jupiter VHS 1256 b

JWST Measurements of 13C, 18O, and 17O in the Atmosphere of Super-Jupiter VHS 1256 b

Asymmetry in the atmosphere of the ultra-hot Jupiter WASP-76 b

A Combined Ground-based and JWST Atmospheric Retrieval Analysis: Both IGRINS and NIRSpec Agree that the Atmosphere of WASP-77A b Is Metal-poor

Contact Info

Product

Resources

About

JWST Measurements of ¹³C, ¹⁸O, and ¹⁷O in the Atmosphere of Super-Jupiter VHS 1256 b

JWST Measurements of ¹³C, ¹⁸O, and ¹⁷O in the Atmosphere of Super-Jupiter VHS 1256 b