Transmission spectral properties of clouds for hot Jupiter exoplanets

By H. Wakeford, D. Sing. 2014

171 citations recorded by the source corpus.

Clouds have an important role in the atmospheres of planetary bodies. It is expected that, like all the planetary bodies in our solar system, exoplanet atmospheres will also have substantial cloud coverage, and evidence is mounting for clouds in a number of hot Jupiters. In order to better characterise planetary atmospheres we need to consider the effects these clouds will have on the observed broadband transmission spectra. Here we examine the expected cloud condensate species for hot Jupiter exoplanets and the effects of various grain sizes and distributions on the resultant transmission spectra from the optical to infrared, which can be used as a broad framework when interpreting exoplanet spectra. We note that significant infrared absorption features appear in the computed transmission spectrum, the result of vibrational modes between the key species in each condensate, which can potentially be very constraining. While it may be hard to differentiate between individual condensates in the broad transmission spectra, it may be possible to discern different vibrational bonds, which can distinguish between cloud formation scenarios such as condensate clouds or photochemically generated species. Vibrational mode features are shown to be prominent when the clouds are composed of small sub-micron sized particles and can be associated with an accompanying optical scattering slope. These infrared features have potential implications for future exoplanetary atmosphere studies conducted with JWST, where such vibrational modes distinguishing condensate species can be probed at longer wavelengths.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/fe3bac4d4dc02ab9b8f31254d8e6df4b85b1accb

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In Astronomy and Astrophysics

1. N. Madhusudhan
2. Jon Fortney
3. A. Showman
4. M. Marley
5. D. Sing
6. V. Parmentier
7. H. Knutson
8. D. Deming

Citations in the corpus

• ExoMol line lists – XVIII. The high-temperature spectrum of VO (2016, background): “…et al. 2010; Madhusudhan & Seager 2010; Huitson et al. 2012; Spiegel & Burrows 2013; Gibson et al. 2013; Parmentier et al. 2013; Agúndez et al. 2014; Hoeijmakers et al. 2015; Schwarz et al. 2015; Haynes et al. 2015; Wakeford & Sing 2015) about a possible temperature c© 2002 The Authors Table 1.”
• A CONSISTENT RETRIEVAL ANALYSIS OF 10 HOT JUPITERS OBSERVED IN TRANSMISSION (2016, background): “At cooler temperatures near ∼1000K, the expected condensible species of MnS, Na2S and KCl are all highly scattering, while at temperatures near 1500 K iron clouds could form which may be more grey (Wakeford & Sing 2015).”
• HST PanCET Program: A Cloudy Atmosphere for the Promising JWST Target WASP-101b (2017, methodology): “Obscuring condensate clouds in planetary atmospheres can remove low abundance absorbers from the gas phase, obscure absorption features from gases at deeper levels (Sing et al. 2016), scatter incoming radiation, and add their own absorption features (Wakeford & Sing 2015; Wakeford et al. 2017).”
• Exoplanetary Atmospheres: Key Insights, Challenges, and Prospects (2019, background): “On the other hand, various studies have explored the range of cloud compositions observable with existing and upcoming facilities (176, 274, 205), spanning from refractory clouds in high-temperature atmospheres to volatile clouds in low-temperature atmospheres.”
• TRANSITIONS IN THE CLOUD COMPOSITION OF HOT JUPITERS (2016, methodology): “Transit spectroscopy can also provide insights on the cloud composition by measuring the cloud coverage at the limb of the planet or by directly measuring the spectral signature of the cloud species (Wakeford & Sing 2015).”