Hydrogen cyanide in nitrogen-rich atmospheres of rocky exoplanets

Rimmer, Paul B.; Rugheimer, Sarah

doi:10.1016/j.icarus.2019.02.020

Cited by 98 publications

(96 citation statements)

References 58 publications

(81 reference statements)

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“…For the ultraviolet transport, a 'mysterious absorber' is included 46 . For our chemical network, we use STAND2019 47 , which includes H/C/N/O species, adding a limited S/Cl/P network relevant for Venus by adapting published low-and middle-atmosphere networks 46,48,49 and developing an estimate for thermal decomposition. The Supplementary Information discusses additional reactions and constants [50][51][52][53][54][55] and major uncertainties.…”

Section: Calculation Of So 2 Contaminationmentioning

confidence: 99%

Phosphine gas in the cloud decks of Venus

et al. 2020

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Measurements of trace gases in planetary atmospheres help us explore chemical conditions different to those on Earth. Our nearest neighbour, Venus, has cloud decks that are temperate but hyperacidic. Here we report the apparent presence of phosphine (PH 3) gas in Venus's atmosphere, where any phosphorus should be in oxidized forms. Single-line millimetre-waveband spectral detections (quality up to ~15σ) from the JCMT and ALMA telescopes have no other plausible identification. Atmospheric PH 3 at ~20 ppb abundance is inferred. The presence of PH 3 is unexplained after exhaustive study of steady-state chemistry and photochemical pathways, with no currently known abiotic production routes in Venus's atmosphere, clouds, surface and subsurface, or from lightning, volcanic or meteoritic delivery. PH 3 could originate from unknown photochemistry or geochemistry, or, by analogy with biological production of PH 3 on Earth, from the presence of life. Other PH 3 spectral features should be sought, while in situ cloud and surface sampling could examine sources of this gas.

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Section: Calculation Of So 2 Contaminationmentioning

confidence: 99%

Phosphine gas in the cloud decks of Venus

et al. 2020

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“…Some cyanamide can also generated photochemically near the interface of the atmosphere and the vent surface (discussed by [28]):…”

Section: Surface Hydrothermal Vents With Carbon-nitrogen-rich Magma Dmentioning

confidence: 99%

Origin of Life’s Building Blocks in Carbon- and Nitrogen-Rich Surface Hydrothermal Vents

Rimmer

Shorttle

2019

Life

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There are two dominant and contrasting classes of origin of life scenarios: those predicting that life emerged in submarine hydrothermal systems, where chemical disequilibrium can provide an energy source for nascent life; and those predicting that life emerged within subaerial environments, where UV catalysis of reactions may occur to form the building blocks of life. Here, we describe a prebiotically plausible environment that draws on the strengths of both scenarios: surface hydrothermal vents. We show how key feedstock molecules for prebiotic chemistry can be produced in abundance in shallow and surficial hydrothermal systems. We calculate the chemistry of volcanic gases feeding these vents over a range of pressures and basalt C/N/O contents. If ultra-reducing carbon-rich nitrogen-rich gases interact with subsurface water at a volcanic vent they result in 10 − 3 – 1 M concentrations of diacetylene (C4H2), acetylene (C2H2), cyanoacetylene (HC3N), hydrogen cyanide (HCN), bisulfite (likely in the form of salts containing HSO3−), hydrogen sulfide (HS−) and soluble iron in vent water. One key feedstock molecule, cyanamide (CH2N2), is not formed in significant quantities within this scenario, suggesting that it may need to be delivered exogenously, or formed from hydrogen cyanide either via organometallic compounds, or by some as yet-unknown chemical synthesis. Given the likely ubiquity of surface hydrothermal vents on young, hot, terrestrial planets, these results identify a prebiotically plausible local geochemical environment, which is also amenable to future lab-based simulation.

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“…This, in particular, is of importance for methane-rich atmospheres like those of Jupiter and Titan (see, e.g., Vuitton et al 2007;Lavvas et al 2013;Hörst 2017;García Muñoz et al 2018), respectively. In addition, methane-rich and N 2 -dominated atmospheres can be seen as natural laboratories to study chemical evolution (see, e.g., Kobayashi et al 2017) and its importance for prebiotic chemistry (see, e.g., Rimmer & Rugheimer 2019).…”

Section: Cosmic-ray Induced Ion Chemistrymentioning

confidence: 99%

A new model suite to determine the influence of cosmic rays on (exo)planetary atmospheric biosignatures

Herbst

Grenfell

Sinnhuber

et al. 2019

A&A

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Context. The first opportunity to detect indications for life outside the Solar System may be provided already within the next decade with upcoming missions such as the James Webb Space Telescope (JWST), the European Extremely Large Telescope (E-ELT) and/or the Atmospheric Remote-sensing Infrared Exoplanet Large-survey (ARIEL) mission, searching for atmospheric biosignatures on planets in the habitable zone of cool K-and M-stars. Nevertheless, their harsh stellar radiation and particle environment could lead to photochemical loss of atmospheric biosignatures. Aims. We aim to study the influence of cosmic rays on exoplanetary atmospheric biosignatures and the radiation environment considering feedbacks between energetic particle precipitation, climate, atmospheric ionization, neutral and ion chemistry, and secondary particle generation. Methods. We describe newly-combined state-of-the-art modeling tools to study the impact of the radiation and particle environment, in particular of cosmic rays, on atmospheric particle interaction, the influence on the atmospheric chemistry and the climate-chemistry coupling in a self-consistent model suite. To this end, models like the Atmospheric Radiation Interaction Simulator (AtRIS), the Exoplanetary Terrestrial Ion Chemistry model (ExoTIC), and the updated coupled climate-chemistry model are combined. Results. Besides comparing our results to Earth-bound measurements, we investigate the ozone-production and -loss cycles as well as the atmospheric radiation dose profiles during quiescent solar periods and during the strong solar energetic particle event of February 23, 1956. Further, the scenario-dependent terrestrial transit spectra, as seen by the NIR-Spec infrared spectrometer onboard the JWST, are modeled. Amongst others, we find that the comparatively weak solar event (i) drastically increases the spectral signal of HNO 3 , while (ii) significantly suppressing the spectral feature of ozone. Because of the slow recovery after such events, the latter indicates that ozone might not be a good biomarker for planets orbiting stars with high flaring rates.

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Hydrogen cyanide in nitrogen-rich atmospheres of rocky exoplanets

Cited by 98 publications

References 58 publications

Phosphine gas in the cloud decks of Venus

Phosphine gas in the cloud decks of Venus

Origin of Life’s Building Blocks in Carbon- and Nitrogen-Rich Surface Hydrothermal Vents

A new model suite to determine the influence of cosmic rays on (exo)planetary atmospheric biosignatures

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