Sodium and Potassium Signatures of Volcanic Satellites Orbiting Close-in Gas Giant Exoplanets

Oza, A.; Johnson, R. E.; Lellouch, E.; Schmidt, Carl; Schneider, Nicholas M.; Huang, Chenliang; Gamborino, Diana; Gebek, Andrea; Wyttenbach, A.; Demory, Brice-Olivier; Mordasini, Christoph; Saxena, Prabal; Dubois, David; Moullet, Arielle; Thomas, N.

doi:10.3847/1538-4357/ab40cc

Cited by 55 publications

(90 citation statements)

References 170 publications

(197 reference statements)

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“…Nutrient and metal delivery could come from an orbiting exomoon. Due to tidal forcing from the host planet, an exomoon may send several orders of magnitude more material to the host planet than the amount of material delivered to Earth by meteorites [111]. For comparison's sake, the close-in exomoons studied around giant exoplanets would provide -31 gigatons yr −1 .…”

Section: Nutrient Scarcitymentioning

confidence: 99%

Possibilities for an Aerial Biosphere in Temperate Sub Neptune-Sized Exoplanet Atmospheres

et al. 2021

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The search for signs of life through the detection of exoplanet atmosphere biosignature gases is gaining momentum. Yet, only a handful of rocky exoplanet atmospheres are suitable for observation with planned next-generation telescopes. To broaden prospects, we describe the possibilities for an aerial, liquid water cloud-based biosphere in the atmospheres of sub Neptune-sized temperate exoplanets, those receiving Earth-like irradiation from their host stars. One such planet is known (K2-18b) and other candidates are being followed up. Sub Neptunes are common and easier to study observationally than rocky exoplanets because of their larger sizes, lower densities, and extended atmospheres or envelopes. Yet, sub Neptunes lack any solid surface as we know it, so it is worthwhile considering whether their atmospheres can support an aerial biosphere. We review, synthesize, and build upon existing research. Passive microbial-like life particles must persist aloft in a region with liquid water clouds for long enough to metabolize, reproduce, and spread before downward transport to lower altitudes that may be too hot for life of any kind to survive. Dynamical studies are needed to flesh out quantitative details of life particle residence times. A sub Neptune would need to be a part of a planetary system with an unstable asteroid belt in order for meteoritic material to provide nutrients, though life would also need to efficiently reuse and recycle metals. The origin of life may be the most severe limiting challenge. Regardless of the uncertainties, we can keep an open mind to the search for biosignature gases as a part of general observational studies of sub Neptune exoplanets.

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Section: Nutrient Scarcitymentioning

confidence: 99%

Possibilities for an Aerial Biosphere in Temperate Sub Neptune-Sized Exoplanet Atmospheres

et al. 2021

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“…In the non-thermal regime we consider plasma-driven escape, where we focus on the observed mechanism of atmospheric sputtering (e.g. Haff et al 1981;Johnson 2004;Oza et al 2019). Surface and upper atmospheric heating dominate light atmospheres (H, He), but nevertheless can be calculated for volatile species of any molar mass.…”

Section: Atmospheric Escapementioning

confidence: 99%

Linking the evolution of terrestrial interiors and an early outgassed atmosphere to astrophysical observations

Bower

Kitzmann

Wolf

et al. 2019

A&A

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106

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Context. A terrestrial planet is molten during formation and may remain molten due to intense insolation or tidal forces. Observations favour the detection and characterisation of hot planets, potentially with large outgassed atmospheres. Aims. We aim to determine the radius of hot Earth-like planets with large outgassing atmospheres. Our goal is to explore the differences between molten and solid silicate planets on the mass–radius relationship and transmission and emission spectra. Methods. An interior–atmosphere model was combined with static structure calculations to track the evolving radius of a hot rocky planet that outgasses CO2 and H2O. We generated synthetic emission and transmission spectra for CO2 and H2O dominated atmospheres. Results. Atmospheres dominated by CO2 suppress the outgassing of H2O to a greater extent than previously realised since previous studies applied an erroneous relationship between volatile mass and partial pressure. We therefore predict that more H2O can be retained by the interior during the later stages of magma ocean crystallisation. Formation of a surface lid can tie the outgassing of H2O to the efficiency of heat transport through the lid, rather than the radiative timescale of the atmosphere. Contraction of the mantle, as it cools from molten to solid, reduces the radius by around 5%, which can partly be offset by the addition of a relatively light species (e.g. H2O versus CO2) to the atmosphere. Conclusions. A molten silicate mantle can increase the radius of a terrestrial planet by around 5% compared to its solid counterpart, or equivalently account for a 13% decrease in bulk density. An outgassing atmosphere can perturb the total radius, according to its composition, notably the abundance of light versus heavy volatile species. Atmospheres of terrestrial planets around M-stars that are dominated by CO2 or H2O can be distinguished by observing facilities with extended wavelength coverage (e.g. JWST).

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“…Among the ten current claims for exomoon candidates (Ben-Jaffel & Ballester 2014;Bennett et al 2014;Oza et al 2019;Kipping 2020;Quarles et al 2020;Fox & Wiegert 2021), we chose to study the system Kepler-1625b i (Section 5) -the most convincing exomooon candidate so far -and compare its properties to those of a stable cronomoon. Despite an accurate fitting model for the light curve of this system was not used, we tested its dynamical evolution and detectable features by assuming a face-on transit: this implies that the sum of the rings' tilt and the inclination of the system is ∼ 90°, helping us illustrate another phenomenological explanation of the observations by predicting small values for TTVs and TDVs.…”

Section: Summary and Discussionmentioning

confidence: 99%

Cronomoons: origin, dynamics, and light-curve features of ringed exomoons

Sucerquia,

Alvarado-Montes,

Bayo

et al. 2021

Preprint

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In recent years, technical and theoretical work to detect moons and rings around exoplanets has been attempted. The small mass/size ratios between moons and planets means this is very challenging, having only one exoplanetary system where spotting an exomoon might be feasible (i.e. Kepler-1625b i). In this work, we study the dynamical evolution of ringed exomoons, dubbed cronomoons after their similarity with Cronus (Greek for Saturn), and after Chronos (the epitome of time), following the Transit Timing Variations (TTV) and Transit Duration Variation (TDV) that they produce on their host planet. Cronomoons have extended systems of rings that make them appear bigger than they actually are when transiting in front of their host star. We explore different possible scenarios that could lead to the formation of such circumsatellital rings, and through the study of the dynamical/thermodynamic stability and lifespan of their dust and ice ring particles, we found that an isolated cronomoon can survive for time-scales long enough to be detected and followed up. If these objects exist, cronomoons' rings will exhibit gaps similar to Saturn's Cassini Division and analogous to the asteroid belt's Kirkwood gaps, but instead raised due to resonances induced by the host planet. Finally, we analyse the case of Kepler-1625b i under the scope of this work, finding that the controversial giant moon could instead be an Earth-mass cronomoon. From a theoretical perspective, this scenario can contribute to a better interpretation of the underlying phenomenology in current and future observations.

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Sodium and Potassium Signatures of Volcanic Satellites Orbiting Close-in Gas Giant Exoplanets

Cited by 55 publications

References 170 publications

Possibilities for an Aerial Biosphere in Temperate Sub Neptune-Sized Exoplanet Atmospheres

Possibilities for an Aerial Biosphere in Temperate Sub Neptune-Sized Exoplanet Atmospheres

Linking the evolution of terrestrial interiors and an early outgassed atmosphere to astrophysical observations

Cronomoons: origin, dynamics, and light-curve features of ringed exomoons

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