A Nondetection of Iron in the First High-resolution Emission Study of the Lava Planet 55 Cnc e

Rasmussen, Kaitlin C.; Currie, Miles H.; Hagee, Celeste; van Buchem, Christiaan; Malik, Matej; Savel, Arjun B; Brogi, Matteo; Rauscher, Emily; Meadows, Victoria; Mansfield, Megan; Kempton, Eliza M.-R.; Desert, Jean-Michel; Wardenier, Joost P.; Pino, Lorenzo; Line, Michael; Parmentier, Vivien; Seifahrt, Andreas; Kasper, David; Brady, Madison; Bean, Jacob L.

doi:10.3847/1538-3881/acf28e

Cited by 6 publications

(2 citation statements)

References 43 publications

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“…Similarly, we expect our wavelength solution to be reliable to ∼100 m s −1 , substantially better than the observed shift. Rasmussen et al (2023) demonstrated that the shift in planetary lines within a science exposure can produce a blueshift of several kilometers per second, though we expect this effect to be minimal given the <1 km s −1 velocity shift between successive spectra in the time series. However, we did not attempt to account for the wavelength dependence or non-Gaussian wings of the NIRSPEC LSF (López et al 2020), potentially leading to a model mismatch in the line shapes that could bias the retrieved velocities.…”

Section: Winds and Circulationmentioning

confidence: 81%

Atmospheric Metallicity and C/O of HD 189733 b from High-resolution Spectroscopy

Finnerty,

Xuan,

Xin

et al. 2024

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We present high-resolution K-band emission spectra of the quintessential hot Jupiter HD 189733 b from the Keck Planet Imager and Characterizer. Using a Bayesian retrieval framework, we fit the dayside pressure–temperature profile, orbital kinematics, mass-mixing ratios of H2O, CO, CH4, NH3, HCN, and H2S, and the 13CO/12CO ratio. We measure mass fractions of logH 2 O = − 2.0 − 0.4 + 0.4 and logCO = − 2.2 − 0.5 + 0.5 , and place upper limits on the remaining species. Notably, we find logCH4 < −4.5 at 99% confidence, despite its anticipated presence at the equilibrium temperature of HD 189733 b assuming local thermal equilibrium. We make a tentative (∼3σ) detection of 13CO, and the retrieved posteriors suggest a 12C/13C ratio similar to or substantially less than the local interstellar value. The possible 13C enrichment would be consistent with accretion of fractionated material in ices or in the protoplanetary disk midplane. The retrieved abundances correspond to a substantially substellar atmospheric C/O = 0.3 ± 0.1, while the carbon and oxygen abundances are stellar to slightly superstellar, consistent with core-accretion models which predict an inverse correlation between C/O and metallicity. The specific combination of low C/O and high metallicity suggests significant accretion of solid material may have occurred late in the formation process of HD 189733 b.

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Section: Winds and Circulationmentioning

confidence: 81%

Atmospheric Metallicity and C/O of HD 189733 b from High-resolution Spectroscopy

Finnerty,

Xuan,

Xin

et al. 2024

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“…Second, the recent chemical detections in K2-18 b with JWST demonstrate both the H 2 -rich nature of such atmospheres and the presence of prominent molecules, above any potential cloud decks, in abundances high enough to be detectable. Third, ground-based high-resolution transit spectroscopy is now a proven technique for detecting chemical signatures in hot Jupiters (Snellen et al 2010;Birkby et al 2013;Brogi et al 2018;Sánchez-López et al 2019), with recent efforts directed toward atmospheres of hot rocky exoplanets (Jindal et al 2020;Rasmussen et al 2023;Ridden-Harper et al 2023). Theoretical studies have demonstrated that the same is also feasible for mini-Neptunes orbiting bright M dwarfs (Gandhi et al 2020;Hood et al 2020).…”

Section: Introductionmentioning

confidence: 99%

High-resolution Spectroscopic Reconnaissance of a Temperate Sub-Neptune

Cabot,

Madhusudhan,

Constantinou

et al. 2024

ApJL

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The study of temperate sub-Neptunes is the new frontier in exoplanetary science. A major development in the past year has been the first detection of carbon-bearing molecules in the atmosphere of a temperate sub-Neptune, K2-18 b, a possible Hycean world, with the James Webb Space Telescope (JWST). The JWST is poised to characterize the atmospheres of several other such planets, with important implications for planetary processes in the temperate regime. Meanwhile, ground-based high-resolution spectroscopy has been highly successful in detecting chemical signatures of giant exoplanets, though low-mass planets have remained elusive. In the present work, we report the atmospheric reconnaissance of a temperate sub-Neptune, TOI-732 c, using ground-based high-resolution transmission spectroscopy. The long orbital period and the low systemic velocity result in a low planetary radial velocity during transit, making this system a valuable test bed for high-resolution spectroscopy of temperate sub-Neptunes. We observe high-resolution time-series spectroscopy in the H and K bands during the planetary transit with the IGRINS instrument (R ∼ 45,000) on Gemini-South. Using observations from a single transit, we find marginal evidence (2.2σ) for the presence of methane (CH4) in the atmosphere and no evidence for ammonia (NH3) despite its strong detectability for a cloud-free H2-rich atmosphere. We assess our findings using injection tests with different atmospheric scenarios and find them to be consistent with a high CH4/NH3 ratio and/or the presence of high-altitude clouds. Our results demonstrate the capability of Gemini-S/IGRINS for atmospheric characterization of temperate sub-Neptunes and the complementarity between space- and ground-based facilities in this planetary regime.

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Super-Earths and Superflares

Walsh

2024

Science and Fiction

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A Nondetection of Iron in the First High-resolution Emission Study of the Lava Planet 55 Cnc e

Cited by 6 publications

References 43 publications

Atmospheric Metallicity and C/O of HD 189733 b from High-resolution Spectroscopy

Atmospheric Metallicity and C/O of HD 189733 b from High-resolution Spectroscopy

High-resolution Spectroscopic Reconnaissance of a Temperate Sub-Neptune

Super-Earths and Superflares

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