Periodic Reporting for period 1 - OxyPlanets (Habitability of Exo-Earths in various atmospheric oxidative conditions)
Berichtszeitraum: 2022-10-01 bis 2025-03-31
Among the thousands of extrasolar planets discovered, Earth-like objects focus our attention to seek new habitable worlds. Eleven Earth-sized planets have already been discovered in the Habitable Zone (HZ) of their host-star, including three in the TRAPPIST-1 planetary system. Deciphering their atmospheres is the challenge of the next decade in exoplanetary science, stressing out urgent needs in fundamental data for these objects.
Our aim is to investigate how the atmospheric organic reservoir forms and evolves in the frame of humid exoplanetary atmospheres in Habitable Zone. We will also quantify the impact of theses processes on the climate and on the potentiality for prebiotic chemistry on these planets. We propose to consider the role of organic hazes as prebio-signature: those are nanoparticles chemically produced in the atmosphere. We will address the capacity of exo-Earths atmospheres to produce organic hazes in various oxidative conditions, and their further physical and chemical interactions with atmospheric water.
To tackle these questions, we will combine experiments and models to discover the reactivity that occurs in atmospheres within an extensive range of oxidation conditions. We will experimentally determine the physical properties of the hazes, and then model their radiative impact and their propensity to generate clouds in the atmosphere. We will also experimentally identify the prebiotic molecules composing the hazes that dissolve into clouds. This transfer from the dry organic reservoir towards liquid water is indeed critical for the emergence of life.
The ERC-AdG OxyPlanets project will contribute to interpret and suggest observations for the future NASA-JWST and ESA-ARIEL space missions and the European Large Telescope. Furthermore, it will reinforce our knowledge of the habitability of Earth-like exo-worlds, potentially reappraising the conditions for life to appear on the early-Earth.
Our aim is to investigate how the atmospheric organic reservoir forms and evolves in the frame of humid exoplanetary atmospheres in Habitable Zone. We will also quantify the impact of theses processes on the climate and on the potentiality for prebiotic chemistry on these planets. We propose to consider the role of organic hazes as prebio-signature: those are nanoparticles chemically produced in the atmosphere. We will address the capacity of exo-Earths atmospheres to produce organic hazes in various oxidative conditions, and their further physical and chemical interactions with atmospheric water.
To tackle these questions, we will combine experiments and models to discover the reactivity that occurs in atmospheres within an extensive range of oxidation conditions. We will experimentally determine the physical properties of the hazes, and then model their radiative impact and their propensity to generate clouds in the atmosphere. We will also experimentally identify the prebiotic molecules composing the hazes that dissolve into clouds. This transfer from the dry organic reservoir towards liquid water is indeed critical for the emergence of life.
The ERC-AdG OxyPlanets project will contribute to interpret and suggest observations for the future NASA-JWST and ESA-ARIEL space missions and the European Large Telescope. Furthermore, it will reinforce our knowledge of the habitability of Earth-like exo-worlds, potentially reappraising the conditions for life to appear on the early-Earth.
The recent observations by the James Webb Space Telescop revealed a massive role of the out-of-equilibrium chemistry in temperate exoplanets, which cannot be explained with the simple models often implemented up to now. With the expertise of our group on out-of-equilibrium atmospheric chemistry, we were able to provide the best support to our community to tackle this challenge and to strongly contribute by investigating the importance of atmospheric chemistry in the field of exoplanets.
The work achieved during the first period of the project is threefold:
First we focused on temperate sub-Neptunes, as those are among the most promising exoplanets to be observed by the JWST and ARIEL in terms of habitability. Those are located close or in the habitable zone of their host star. Their atmosphere is hydrogen rich, and exhibits a high metallicity (a large amount of carbon in particular). Their proximity to their star involves an intense evaporation process leading to an efficient hydrogen loss toward the interplanetary medium, and a progressive enrichment in heavier molecules, like methane or carbon dioxide. Temperate sub-Neptunes are therefore to-date considered as key planets for studying how the secondary atmosphere of the early-Earth was formed. In order to investigate the gas-phase chemistry occurring in these exoplanetary atmospheres, we have therefore led a large range of experiments in H2 rich conditions, varying the content in methane vs carbon dioxide. The fine analysis of this large dataset is in progress, and major results are already revealed on the formation of oxydized organic molecules of interest for prebiotic chemistry.
Secondly, we tackled one of the main limitations for the interpretation of the exoplanets observations, which is the lack of knowledge on the optical properties of hazes. We synthesized experimentally a set of analogues of particles representative of various chemical conditions in exoplanetary atmospheres. Then we developed a demanding and rigorous methodology to characterize the particles’ optical properties on the broad UV-Far IR spectral, requiring measurements on multiple devices, among them IR measurements at SOLEIL, French national synchrotron facility. We were thus able to deliver during the first period of the project a pioneer work, providing the first optical properties of exoplanet’s haze in a large 0.3 to 30 μm spectral range, consistent with the JWST measurements.
Finally, another very important achievement concerns the experimental development of a specific reactor for investigating sulfur chemistry. Sulfur chemistry is indeed rather tricky to explore in the lab (corrosive and toxic). It has been therefore very few investigated in the past for planetary science. The chemical databases are poor by lack of experiments. Sulfur chemistry is however of prime importance in a number of planets, where volcanism is present. Our successful and safe experimental development therefore opens large perspectives for research in planetary science and atmospheric chemistry.
The work achieved during the first period of the project is threefold:
First we focused on temperate sub-Neptunes, as those are among the most promising exoplanets to be observed by the JWST and ARIEL in terms of habitability. Those are located close or in the habitable zone of their host star. Their atmosphere is hydrogen rich, and exhibits a high metallicity (a large amount of carbon in particular). Their proximity to their star involves an intense evaporation process leading to an efficient hydrogen loss toward the interplanetary medium, and a progressive enrichment in heavier molecules, like methane or carbon dioxide. Temperate sub-Neptunes are therefore to-date considered as key planets for studying how the secondary atmosphere of the early-Earth was formed. In order to investigate the gas-phase chemistry occurring in these exoplanetary atmospheres, we have therefore led a large range of experiments in H2 rich conditions, varying the content in methane vs carbon dioxide. The fine analysis of this large dataset is in progress, and major results are already revealed on the formation of oxydized organic molecules of interest for prebiotic chemistry.
Secondly, we tackled one of the main limitations for the interpretation of the exoplanets observations, which is the lack of knowledge on the optical properties of hazes. We synthesized experimentally a set of analogues of particles representative of various chemical conditions in exoplanetary atmospheres. Then we developed a demanding and rigorous methodology to characterize the particles’ optical properties on the broad UV-Far IR spectral, requiring measurements on multiple devices, among them IR measurements at SOLEIL, French national synchrotron facility. We were thus able to deliver during the first period of the project a pioneer work, providing the first optical properties of exoplanet’s haze in a large 0.3 to 30 μm spectral range, consistent with the JWST measurements.
Finally, another very important achievement concerns the experimental development of a specific reactor for investigating sulfur chemistry. Sulfur chemistry is indeed rather tricky to explore in the lab (corrosive and toxic). It has been therefore very few investigated in the past for planetary science. The chemical databases are poor by lack of experiments. Sulfur chemistry is however of prime importance in a number of planets, where volcanism is present. Our successful and safe experimental development therefore opens large perspectives for research in planetary science and atmospheric chemistry.
Here we would in particular like to emphasize the third achievement detailed previously and describing our experimental development of a specific reactor for sulfur chemistry.
Sulfur chemistry is rather tricky to adress in the lab (corrosive and toxic) and has been therefore very few investigated in the past in planetary science. The chemical databases are therefore poor by lack of experiments. Sulfur chemistry is however of prime importance in a number of planets, where volcanism is present.
Our successful and safe experimental development therefore opens pioneer perspectives for research in planetary science and atmospheric chemistry.
Sulfur chemistry is rather tricky to adress in the lab (corrosive and toxic) and has been therefore very few investigated in the past in planetary science. The chemical databases are therefore poor by lack of experiments. Sulfur chemistry is however of prime importance in a number of planets, where volcanism is present.
Our successful and safe experimental development therefore opens pioneer perspectives for research in planetary science and atmospheric chemistry.