The discovery of an extraordinary number of extrasolar planets, characterized by an unexpected variety of sizes, masses and orbits, challenges our understanding of the formation and evolution of the planets in the Solar System and the perception of the Earth as the prototypical habitable world. Many exoplanets appear to be rocky and yet more massive than the Earth, with expected pressures and temperatures of hundreds of gigapascal and thousands of Kelvin in their deep interiors. At these conditions, the properties of bridgmanite and ferropericlase, expected to dominate their mantles, are largely unconstrained, limiting our knowledge of their interior structure. Here we used nano-second X-ray diffraction and dynamic compression to experimentally investigate the atomic structure and density of iron oxide (FeO), one of the end-members of the (Mg,Fe)O ferropericlase solid solution, up to 700 GPa, a pressure exceeding the core–mantle boundary of a 5 Earth masses planet. Our data document the stability of the high-pressure cesium-chloride B2 structure above 300 GPa, well below the pressure required for magnesium oxide (MgO) to adopt the same phase. These observations, complemented by the calculation of the binary MgO–FeO phase diagram, reveal complex stratification and rheology inside large terrestrial exoplanets.
Coppari, F., et al. "Implications of the iron oxide phase transition on the interiors of rocky exoplanets." Nature Geoscience, vol. 14, no. 3, Feb. 2021. https://doi.org/10.1038/s41561-020-00684-y
Coppari, F., Smith, R. F., Wang, J., Millot, M., Kim, D., Rygg, J. R., Hamel, S., Eggert, J. H., & Duffy, T. S. (2021). Implications of the iron oxide phase transition on the interiors of rocky exoplanets. Nature Geoscience, 14(3). https://doi.org/10.1038/s41561-020-00684-y
Coppari, F., Smith, R. F., Wang, J., et al., "Implications of the iron oxide phase transition on the interiors of rocky exoplanets," Nature Geoscience 14, no. 3 (2021), https://doi.org/10.1038/s41561-020-00684-y
@article{osti_1814682,
author = {Coppari, F. and Smith, R. F. and Wang, J. and Millot, M. and Kim, D. and Rygg, J. R. and Hamel, S. and Eggert, J. H. and Duffy, T. S.},
title = {Implications of the iron oxide phase transition on the interiors of rocky exoplanets},
annote = {The discovery of an extraordinary number of extrasolar planets, characterized by an unexpected variety of sizes, masses and orbits, challenges our understanding of the formation and evolution of the planets in the Solar System and the perception of the Earth as the prototypical habitable world. Many exoplanets appear to be rocky and yet more massive than the Earth, with expected pressures and temperatures of hundreds of gigapascal and thousands of Kelvin in their deep interiors. At these conditions, the properties of bridgmanite and ferropericlase, expected to dominate their mantles, are largely unconstrained, limiting our knowledge of their interior structure. Here we used nano-second X-ray diffraction and dynamic compression to experimentally investigate the atomic structure and density of iron oxide (FeO), one of the end-members of the (Mg,Fe)O ferropericlase solid solution, up to 700 GPa, a pressure exceeding the core–mantle boundary of a 5 Earth masses planet. Our data document the stability of the high-pressure cesium-chloride B2 structure above 300 GPa, well below the pressure required for magnesium oxide (MgO) to adopt the same phase. These observations, complemented by the calculation of the binary MgO–FeO phase diagram, reveal complex stratification and rheology inside large terrestrial exoplanets.},
doi = {10.1038/s41561-020-00684-y},
url = {https://www.osti.gov/biblio/1814682},
journal = {Nature Geoscience},
issn = {ISSN 1752-0894},
number = {3},
volume = {14},
place = {United States},
publisher = {Nature Publishing Group},
year = {2021},
month = {02}}
SHOCK COMPRESSION OF CONDENSED MATTER - 2003: Proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter, AIP Conference Proceedingshttps://doi.org/10.1063/1.1780457