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Measuring the melting curve of iron at super-Earth core conditions
Ist Teil von
Science (American Association for the Advancement of Science), 2022-01, Vol.375 (6577), p.202-205
Ort / Verlag
United States: The American Association for the Advancement of Science
Erscheinungsjahr
2022
Quelle
Science Online科学在线
Beschreibungen/Notizen
The discovery of more than 4500 extrasolar planets has created a need for modeling their interior structure and dynamics. Given the prominence of iron in planetary interiors, we require accurate and precise physical properties at extreme pressure and temperature. A first-order property of iron is its melting point, which is still debated for the conditions of Earth’s interior. We used high-energy lasers at the National Ignition Facility and in situ x-ray diffraction to determine the melting point of iron up to 1000 gigapascals, three times the pressure of Earth’s inner core. We used this melting curve to determine the length of dynamo action during core solidification to the hexagonal close-packed (hcp) structure. We find that terrestrial exoplanets with four to six times Earth’s mass have the longest dynamos, which provide important shielding against cosmic radiation.