Cross-sections for heavy atmospheres: H<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"><mml:msub><mml:mrow/><mml:mn>2</mml:mn></mml:msub></mml:math>O continuum

Anisman, Lara; Chubb, Katy L.; Elsey, Jonathan; Al-Refaie, Ahmed; Changeat, Quentin; Yurchenko, Sergei N.; Tennyson, Jonathan; Tinetti, Giovanna

doi:10.1016/j.jqsrt.2021.108013

Cited by 13 publications

(6 citation statements)

References 30 publications

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“…In each free chemistry case, all molecular abundances were allowed to vary from log(VMR) = −1 to log(VMR) = −12, where VMR is the volume-mixing ratio. Higher mixing are not expected in the majority of these atmospheres and these would also necessitate accounting for self-broadening of the molecular lines (Anisman et al 2022a(Anisman et al , 2022b. For the equilibrium chemistry retrievals, the metallicity was allowed to vary from 0.1 to 100 and the C/O ratio had bounds of 0.1 and 2.…”

Section: Retrieval Setupmentioning

confidence: 99%

Exploring the Ability of Hubble Space Telescope WFC3 G141 to Uncover Trends in Populations of Exoplanet Atmospheres through a Homogeneous Transmission Survey of 70 Gaseous Planets

Edwards,

Changeat,

Tsiaras

et al. 2023

ApJS

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We present analysis of the atmospheres of 70 gaseous extrasolar planets via transit spectroscopy with Hubble’s Wide Field Camera 3 (WFC3). For over half of these, we statistically detect spectral modulation that our retrievals attribute to molecular species. Among these, we use Bayesian hierarchical modeling to search for chemical trends with bulk parameters. We use the extracted water abundance to infer the atmospheric metallicity and compare it to the planet’s mass. We also run chemical equilibrium retrievals, fitting for the atmospheric metallicity directly. However, although previous studies have found evidence of a mass–metallicity trend, we find no such relation within our data. For the hotter planets within our sample, we find evidence for thermal dissociation of dihydrogen and water via the H− opacity. We suggest that the general lack of trends seen across this population study could be due to (i) the insufficient spectral coverage offered by the Hubble Space Telescope’s WFC3 G141 band, (ii) the lack of a simple trend across the whole population, (iii) the essentially random nature of the target selection for this study, or (iv) a combination of all the above. We set out how we can learn from this vast data set going forward in an attempt to ensure comparative planetology can be undertaken in the future with facilities such as the JWST, Twinkle, and Ariel. We conclude that a wider simultaneous spectral coverage is required as well as a more structured approach to target selection.

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Section: Retrieval Setupmentioning

confidence: 99%

Exploring the Ability of Hubble Space Telescope WFC3 G141 to Uncover Trends in Populations of Exoplanet Atmospheres through a Homogeneous Transmission Survey of 70 Gaseous Planets

Edwards,

Changeat,

Tsiaras

et al. 2023

ApJS

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“…In each free chemistry case, all molecular abundances are allowed to vary from log(VMR) = −1 to log(VMR) = −15. Higher mixing is not expected in the hydrogen-dominated atmosphere of LTT 9779 b and, in any case, these would also necessitate accounting for self-broadening of the molecular lines (Anisman et al 2022a(Anisman et al , 2022b. We explore using both an isothermal temperature profile and an NPoint profile.…”

Section: Atmospheric Retrievalsmentioning

confidence: 99%

Characterizing a World Within the Hot-Neptune Desert: Transit Observations of LTT 9779 b with the Hubble Space Telescope/WFC3

Edwards,

Changeat,

Tsiaras

et al. 2023

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We present an atmospheric analysis of LTT 9779 b, a rare planet situated in the hot-Neptune desert, that has been observed with Hubble Space Telescope (HST)/WFC3 with G102 and G141. The combined transmission spectrum, which covers 0.8–1.6 μm, shows a gradual increase in transit depth with wavelength. Our preferred atmospheric model shows evidence for H2O, CO2, and FeH with a significance of 3.1σ, 2.4σ, and 2.1σ, respectively. In an attempt to constrain the rate of atmospheric escape for this planet, we search for the 1.083 μm helium line in the G102 data but find no evidence of excess absorption that would indicate an escaping atmosphere using this tracer. We refine the orbital ephemerides of LTT 9779 b using our HST data and observations from TESS, searching for evidence of orbital decay or apsidal precession, which are not found. The phase-curve observation of LTT 9779 b with JWST NIRISS should provide deeper insights into the atmosphere of this planet and the expected atmospheric escape might be detected with further observations concentrated on other tracers such as Lyα.

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“…In (H 2 O) 2 such states are thought to play a significant but poorly characterized role in absorption the Earth atmosphere 9,10 and, by analogy in the atmospheres water-rich exoplanets. 11 These states of (H 2 O) 2 currently cannot be characterized in high resolution experiments. As a consequence the HF dimer discrepancies provide a unique means of characterizing the corresponding discrepancies in water dimer spectra.…”

Section: Introductionmentioning

confidence: 99%

Highly accurate HF dimer ab initio potential energy surface

Ovsyannikov

Makhnev

Zobov

et al. 2022

The Journal of Chemical Physics

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A very accurate, (HF)$_2$ potential energy surface (PES)is constructed based on \ai\ calculations performed% at the CCSD(T) level of theory with an aug-cc-pVQZ-F12basis set at about 152~000 points.A higher correlation correction is computed at CCSDT(Q) level for 2000 points and is considered alongside other more minorcorrections due to relativity, core-valence correlation and Born-Oppenheimer failure.The analytical surface constructed uses 500 constants to reproduce the \ai\ points with a standard deviation of 0.3 \cm.Vibration-rotation-inversion energy levels of the HF dimer are computed for this PES by variational solution of the nuclear-motionSchr\"{o}dinger using program WAVR4. Calculations over an extended range of rotationally excited states show very good agreementwith the experimental data. In particular the known empirical rotational constants $B$ for the ground vibrational states are predicted to better than about 2 MHz.$B$ constants for excited vibrational states are reproduced several times more accurately than by previous calculations. %The experimental dissociation energy of the HF dimer is reproduced \ai\ within the experimental accuracy of about 1 \cm\ for the first time. This level of accuracy is shown to extend to higher excited inter-molecular vibrational states $v$ and higher excited rotational quantum numbers $(J,K_a)$.

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Cross-sections for heavy atmospheres: H2O continuum

Cited by 13 publications

References 30 publications

Exploring the Ability of Hubble Space Telescope WFC3 G141 to Uncover Trends in Populations of Exoplanet Atmospheres through a Homogeneous Transmission Survey of 70 Gaseous Planets

Exploring the Ability of Hubble Space Telescope WFC3 G141 to Uncover Trends in Populations of Exoplanet Atmospheres through a Homogeneous Transmission Survey of 70 Gaseous Planets

Characterizing a World Within the Hot-Neptune Desert: Transit Observations of LTT 9779 b with the Hubble Space Telescope/WFC3

Highly accurate HF dimer ab initio potential energy surface

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