ozgeozg

• Mamonova, E.; Herbst, K.; Kofman, V.; Ozgurel, Ozge; Kowalski, A. F. & Wedemeyer, S. [Vis alle 7 forfattere av denne artikkelen] (2026). Stellar-flare-driven evolution of primordial early exo-Earth atmospheres: Insights from the young M dwarf flare model. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 710. doi: 10.1051/0004-6361/202558763. Fulltekst i vitenarkiv Vis sammendrag

  Context . M dwarfs are key targets for terrestrial exoplanet studies, with prospects for atmospheric spectroscopy. However, strong stellar magnetic activity and frequent flaring require modelling efforts to assess their impact on planetary atmospheres. Aims . We investigated one year of atmospheric chemical evolution of a young exo-Earth orbiting an active M dwarf by coupling our young M dwarf flare (YMDF) model of stellar activity with the photochemical kinetic code VULCAN. Methods . The YMDF model provides time-resolved spectral energy distributions for high- and low-energy electron beam–driven flares, which are used as external radiative inputs to VULCAN to compute the time-dependent photochemistry and kinetics for different primordial atmospheric scenarios. Results . We present the impact of stellar flares on atmospheres with a varying water vapour content, ranging from a plausible primordial atmosphere with solar abundances (representative of a planet-forming region in a dissipating protoplanetary disk) to an extreme water-steam atmosphere with other species reduced to trace abundances. This was explored across several configurations: variable flux in the YMDF model, the previous model representing an active but older M dwarf with 10 or 400K additional bottom boundary heat flux, and a constant stellar flux model. Conclusions . Our study suggests that compared to the previous model, the YMDF model produces synthetic flares that exert significantly greater stress on primordial atmospheres, regardless of the water-vapour content. Increased activity and prevalence of mid-size flares has the potential to induce permanent changes in atmospheric mixing ratios, especially in species with low abundances.

• Saurety, Adrien; Ozgurel, Ozge; Mohn, Chris Erik & Caracas, Razvan (2024). Diffusion, chemical bonding, and kinetic fractionation of noble gases in the primordial magma ocean. Geochimica et Cosmochimica Acta. ISSN 0016-7037. 378, s. 144–152. doi: 10.1016/j.gca.2024.06.021. Fulltekst i vitenarkiv Vis sammendrag

  Noble gases record in their radiogenic/non-radiogenic isotope ratios the traces of accretion history and degassing events from the early Earth, including giant impacts and the magma ocean stage, to large-scale recent volcanism. The diffusional behavior of noble gases in silicate magmas is one of the essential parameters needed to correctly model devolatilization from the magma ocean and subsequent volcanic eruptions. Here, we study the diffusivity of He, Ne, Ar, Kr, and Xe in molten pyrolite using ab initio molecular dynamics. We find that the diffusivity of the noble gases decreases with increasing atomic size. The diffusion of Ar is comparable to that of Mg. We compute the partial molar volumes and find that at high pressure, He is almost one order of magnitude more compressible than the heavier noble gases. The analysis of the speciation of the noble gases in the melt indicates that the lifetime of the coordination polyhedra formed with O is not sensitive to the mass of the noble gases. Finally, we compute the electron localization function along the Xe–O interatomic vectors and show that there is no chemical bonding between the Xe and surrounding O atoms from the hosting silicate melt.

• Ozgurel, Ozge & Caracas, Razvan (2023). The magma ocean was a huge helium reservoir in the early Earth. Geochemical Perspectives Letters. ISSN 2410-339X. 25, s. 46–50. doi: 10.7185/geochemlet.2314. Fulltekst i vitenarkiv Vis sammendrag

  Helium from mantle-derived rocks bears in its isotopic ratios the traces of Earth differentiation, degassing, and long term geodynamic evolution. The low 4He/3He ratio of rocks whose origins are in the deep mantle, like ocean island basalts (OIBs), reflect potentially concealed geochemical reservoirs rich in primordial 3He and isolated from the surface. Here we search for the geological repository of primordial He lasting from the core formation. For this, we determine the chemical behaviour of He in the magma ocean (MO) during core formation. We perform ab initio molecular dynamics simulations at temperatures and pressures along the MO adiabat. Our results show that primordial He was largely trapped in MO. At the top, under the hot dense early atmosphere, He remained mainly in the MO and degassed only later, at low atmospheric pressure. At the bottom, He partitions preferentially into the MO rather than the liquid core. The origin of the OIBs reflects a large contribution and contamination from mantle sources and no contribution from the top of the outer core, depleted in primordial He. We suggest the search for the He reservoirs should be done at the base of the solid mantle.

• Ozgurel, Ozge; Duflot, Denis; Masella, Michel; Réal, Florent & Toubin, Céline (2022). A Molecular Scale Investigation of Organic/Inorganic Ion Selectivity at the Air−Liquid Interface. ACS Earth and Space Chemistry. 6, s. 1698–1716. doi: 10.1021/acsearthspacechem.1c00394. Fulltekst i vitenarkiv
• Luspay-Kuti, Adrienn; Mousis, Olivier; Pauzat, Françoise; Ozgurel, Ozge; Ellinger, Yves & Lunine, Jonathan I. [Vis alle 10 forfattere av denne artikkelen] (2022). Dual storage and release of molecular oxygen in comet 67P/Churyumov–Gerasimenko. Nature Astronomy. 6, s. 724–730. doi: 10.1038/s41550-022-01614-1. Fulltekst i vitenarkiv

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