The Peculiar Volatile Composition of CO-dominated Comet C/2016 R2 (PanSTARRS)

McKay, Adam; DiSanti, M. A.; Kelley, Michael S. P.; Knight, Matthew M.; Womack, Maria; Wierzchoś, Kacper; Pinto, Olga Harrington; Bonev, B. P.; Villanueva, Gerónimo; Russo, N. Dello; Cochran, A. L.; Biver, Nicolás; Bauer, J. M.; Vervack, R. J.; Gibbs, Erika; Roth, Nathan X.; Kawakita, Hideyo

doi:10.3847/1538-3881/ab32e4

Cited by 71 publications

(78 citation statements)

References 95 publications

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“…With this limit on the CMF, we are assuming that the exoplanets have not been exposed to events during or after their formation that could have stripped away all of their mantle, such as mantle evaporation or giant impacts. In addition, the maximum WMF is set to 80%, which is the average water proportion found in comets in the Solar System (McKay et al 2019). The prior distribution for the mass is a Gaussian distribution whose mean and standard deviations correspond to the central value and uncertainties of the observations.…”

Section: Mcmc Bayesian Analysismentioning

confidence: 99%

Characterisation of the hydrospheres of TRAPPIST-1 planets

Acuña

Deleuil

Mousis

et al. 2021

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Context. Planetary mass and radius data suggest that low-mass exoplanets show a wide variety of densities. This includes sub-Neptunes, whose low densities can be explained with the presence of a volatile-rich layer. Water is one of the most abundant volatiles, which can be in the form of different phases depending on the planetary surface conditions. To constrain their composition and interior structure, models must be developed that accurately calculate the properties of water at its different phases. Aims. We present an interior structure model that includes a multiphase water layer with steam, supercritical, and condensed phases. We derive the constraints for planetary compositional parameters and their uncertainties, focusing on the multi-planetary system TRAPPIST-1, which presents both warm and temperate planets. Methods. We use a 1D steam atmosphere in radiative-convective equilibrium with an interior whose water layer is in supercritical phase self-consistently. For temperate surface conditions, we implement liquid and ice Ih to ice VII phases in the hydrosphere. We adopt a Markov chain Monte Carlo inversion scheme to derive the probability distributions of core and water compositional parameters. Results. We refine the composition of all planets and derive atmospheric parameters for planets ‘b’ and ‘c’. The latter would be in a post-runaway greenhouse state and could be extended enough to be probed by space missions such as JWST. Planets ‘d’ to ‘h’ present condensed ice phases, with maximum water mass fractions below 20%. Conclusions. The derived amounts of water for TRAPPIST-1 planets show a general increase with semi-major axis, with the exception of planet d. This deviation from the trend could be due to formation mechanisms, such as migration and an enrichment of water in the region where planet d formed, or an extended CO2-rich atmosphere.

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Section: Mcmc Bayesian Analysismentioning

confidence: 99%

Characterisation of the hydrospheres of TRAPPIST-1 planets

Acuña

Deleuil

Mousis

et al. 2021

A&A

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“… 2018 ; McKay et al. 2019 ; Opitom et al. 2019 ), or variation in relative abundance of different species with heliocentric distance (e.g., C/2009 P1; Feaga et al.…”

Section: Observation Of Cometsmentioning

confidence: 99%

On the Origin and Evolution of the Material in 67P/Churyumov-Gerasimenko

et al. 2020

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Primitive objects like comets hold important information on the material that formed our solar system. Several comets have been visited by spacecraft and many more have been observed through Earth-and space-based telescopes. Still our understanding remains limited. Molecular abundances in comets have been shown to be similar to interstellar ices and thus indicate that common processes and conditions were involved in their formation. The samples returned by the Stardust mission to comet Wild 2 showed that the bulk refractory material was processed by high temperatures in the vicinity of the early sun. The recent Rosetta mission acquired a wealth of new data on the composition of comet 67P/Churyumov-Gerasimenko (hereafter 67P/C-G) and complemented earlier observations of other comets. The isotopic, elemental, and molecular abundances of the volatile, semivolatile, and refractory phases brought many new insights into the origin and processing of the incorporated material. The emerging picture after Rosetta is that at least part of the volatile material was formed before the solar system and that cometary nuclei agglomerated over a wide range of heliocentric distances, different from where they are found today. Deviations from bulk solar system abundances indicate that the material was not fully homogenized at the location of comet formation, despite the radial mixing implied by the Stardust results. Post-formation evolution of the material might play an important role, which further

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“…This demonstrates a relatively unusual composition for 2I/Borisov's coma: HCN is close to the average abundance of 0.12% observed previously in Solar System comets 20 , while the CO abundance is much higher than the average value of 4% 22 . Even Oort Cloud comets previously designated as CO-rich only have CO/H 2 O ratios in the range 10% to 24% 22 (see also Supplementary Table 1), with the exception of the recently discovered, peculiar Oort Cloud comet C/2016 R2 (PanSTARRS), which had CO/H 2 O = 30,800% 23 .…”

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confidence: 99%