A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve

Kempton, Eliza M.-R.; Bean, Jacob L.; Steinrueck, Maria E.; Piette, Anjali A. A.; Parmentier, Vivien; Malsky, Isaac; Roman, Michael T.; Rauscher, Emily; Bell, Taylor; Xue, Qiao; Taylor, Jake; Savel, Arjun B.; Arnold, Ken; Nixon, Matthew C.; Stevenson, Kevin B.; Mansfield, Megan; Kendrew, Sarah; Zieba, Sebastian; Ducrot, Elsa; Dyrek, Achrène; Lagage, Pierre-Olivier; Stassun, Keivan G.; Henry, Gregory W.; Barman, Travis; Lupu, Roxana; Malik, Matej; Kataria, Tiffany; Ih, Jegug; Fu, Guangwei; Welbanks, Luis; McGill, Peter

doi:10.1038/s41586-023-06159-5

Cited by 28 publications

(35 citation statements)

References 97 publications

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“…However, some nondetections seem highly constraining, including the Kasper et al (2020) nondetection of GJ 1214b (also see the nondetection of Spake et al 2022), which falls 1.1 dex below the trend line, and that of GJ 9827d, which falls 0.5 dex below even the η = 0.1 line. Recent JWST/ MIRI observations of GJ 1214b suggest that its atmosphere is of high mean molecular weight (Kempton et al 2023);however, Orell-Miquel et al (2022) reported a tentative detection of escaping helium. GJ 9827d is a small planet (2.0 R ⊕ ) orbiting a several-gigayear-old star (Rice et al 2019), andCarleo et al (2021) suggested that it may have lost any H/He envelope, although its low density of 2.5 g cm −3 would be puzzling if that were the case.…”

Section: Discussionmentioning

confidence: 99%

“…These observations are important for testing mass-loss models, which suffer from large theoretical uncertainties. For example, mini-Neptunes may have very high metallicity atmospheres (Kempton et al 2023), which have lower hydrogen/helium abundance, slower outflows (because of the higher mean molecular weight), and higher temperatures, suppressing the outflow (Zhang et al 2022a). Planetary magnetic fields can affect mass loss in complex ways (e.g., Ramstad & Barabash 2021;Schreyer et al 2023).…”

Section: Introductionmentioning

confidence: 99%

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Outflowing Helium from a Mature Mini-Neptune

Zhang,

Dai,

Bean

et al. 2023

ApJL

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We announce the detection of escaping helium from TOI 2134b, a mini-Neptune a few gigayears old. The average in-transit absorption spectrum shows a peak of 0.37% ± 0.05% and an equivalent width of W avg = 3.3 ± 0.3 mÅ. Among all planets with helium detections, TOI 2134b is the only mature mini-Neptune, has the smallest helium signal, and experiences the lowest X-ray and ultraviolet (XUV) flux. Putting TOI 2134b in the context of all other helium detections, we report the detection of a strong (p = 3.0 × 10−5) and theoretically expected correlation between F XUV/ρ XUV (proportional to the energy-limited mass-loss rate) and R * W avg (roughly proportional to the observationally inferred mass-loss rate). Here W avg is the equivalent width of the helium absorption, and ρ XUV is the density of the planet within the XUV photosphere, but the correlation is similarly strong if we use the optical photosphere. Having the lowest value on both axes, TOI 2134b anchors the relation. We encourage further observations to fill in the missing regions of this parameter space and improve estimates of F XUV.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Outflowing Helium from a Mature Mini-Neptune

Zhang,

Dai,

Bean

et al. 2023

ApJL

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“…The exquisite precision measurements available from JWST and ground-based high-resolution spectroscopy are revolutionizing atmospheric characterization by probing inherently 3D atmospheric properties (e.g., Ehrenreich et al 2020;Beltz et al 2021;Herman et al 2022;Pino et al 2022;Prinoth et al 2022;Coulombe et al 2023;Kempton et al 2023;van Sluijs et al 2023). In the upcoming decade, new high-resolution spectrographs on 30 m class telescopes will allow the analysis of spectra from a plethora of exoplanets and a greater understanding of the 3D nature of hot Jupiters.…”

Section: Discussionmentioning

confidence: 99%

A Direct Comparison between the Use of Double Gray and Multiwavelength Radiative Transfer in a General Circulation Model with and without Radiatively Active Clouds

Malsky,

Rauscher,

Roman

et al. 2024

ApJ

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Inhomogeneous cloud formation and wavelength-dependent phenomena are expected to shape hot Jupiter atmospheres. We present a general circulation model with multiwavelength “picket fence” radiative transfer and radiatively active, temperature-dependent clouds, and compare the results to those of a double gray routine. The double gray method inherently fails to model polychromatic effects in hot Jupiter atmospheres, while picket fence captures these non-gray aspects and performs well compared to fully wavelength-dependent methods. We compare both methods with radiatively active clouds and cloud-free models, assessing the limitations of the double gray method. Although there are broad similarities, the picket fence models have larger dayside–nightside temperature differences, nonisothermal upper atmospheres, and multiwavelength effects in the presence of radiatively active clouds. We model the well-known hot Jupiters HD 189733 b and HD 209458 b. For the hotter HD 209458 b, the picket fence method prevents clouds from thermostating dayside temperatures, resulting in hotter upper atmospheres and the dissipation of dayside clouds. Differences in the temperature structures are then associated with nuanced differences in the circulation patterns and clouds. Models of the cooler HD 189733 b have global cloud coverage, regardless of the radiative transfer scheme, whereas there are larger differences in the models of HD 209458 b, particularly in the extent of the partial cloud coverage on its dayside. This results in minor changes to the thermal and reflected light phase curves of HD 189733 b, but more significant differences for the picket fence and double gray versions of HD 209458 b.

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“…Transmission spectral components at the transit ingress and egress can be separated to individually probe the morning and evening limbs (Espinoza & Jones 2021;Grant & Wakeford 2023). Thermal emission observations at different orbital phases further reveal the spatial variation across the planet (Stevenson et al 2014;Mendonça et al 2018a;Chubb & Min 2022;Kempton et al 2023). While most previous studies focused on temperature variations, our integrated approach enables us to examine the effects of chemical variations regulated by both vertical and horizontal transport.…”

Section: Features In the Synthetic Spectramentioning

confidence: 99%

Day–Night Transport-induced Chemistry and Clouds on WASP-39b: Gas-phase Composition

Tsai,

Moses,

Powell

et al. 2023

ApJL

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JWST has recently detected the first robust photochemical product on an exoplanet: sulfur dioxide (SO2) on WASP-39b. The data from the NIRISS instrument also reveal signs of partial coverage of clouds. Most of the previous studies have focused on interpreting spectral data with 1D models. To explore how the chemical species and cloud particles are altered by global circulation, we applied a 2D photochemical model and a 2D microphysical cloud model separately to postprocess the thermal and dynamical structures simulated by a 3D general circulation model of WASP-39b. We found that SO2 produced by photochemistry on the dayside can be transported to the nightside owing to the efficient replenishment of horizontal transport. The morning–evening limb differences in methane (CH4) abundances predicted by the 1D models disappeared after horizontal transport is included. Similarly, the inclusion of horizontal transport also reduced the limb differences in SO2. Our modeling results suggest that the fast zonal wind results in minimal or negligible limb asymmetry in composition. Based on the synthetic spectra generated by our 2D atmosphere simulations, we propose that observing SO2 absorption in the emission spectra of WASP-39b at different phases may offer opportunities to probe the horizontal quenching process of photochemical products. We will focus on the gas-phase chemistry in this paper and leave the results regarding clouds in the subsequent paper as part of the series.

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A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve

Cited by 28 publications

References 97 publications

Outflowing Helium from a Mature Mini-Neptune

Outflowing Helium from a Mature Mini-Neptune

A Direct Comparison between the Use of Double Gray and Multiwavelength Radiative Transfer in a General Circulation Model with and without Radiatively Active Clouds

Day–Night Transport-induced Chemistry and Clouds on WASP-39b: Gas-phase Composition

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