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date: 06 November 2024

Experimental Studies of Condensation in the Solar Nebula and Circumstellar Outflowslocked

Experimental Studies of Condensation in the Solar Nebula and Circumstellar Outflowslocked

  • Aki TakigawaAki TakigawaThe University of Tokyo

Summary

Characteristics of minerals in primitive chondrites, micrometeorites, and interplanetary dust particles (IDPs) such as chemical composition, crystal structures, textures, size, and shape indicate that solids and gases hardly reached equilibrium in the solar nebula. They may record a part of physicochemical conditions where dust formed or altered in the solar nebula or their parent bodies. Even the presence or absence of the minerals constrain the conditions in which they can survive or disappear. On the basis of the thermodynamical equilibrium models, which succeeded in predicting minerals stable in each temperature and pressure condition, laboratory experiments have played crucial roles in understanding kinetically controlled processes, such as evaporation, condensation (nucleation and growth), and chemical reactions, and deducing formation and alteration conditions in the solar nebula and their parent bodies from observations of primitive extraterrestrial materials.

In laboratories, it is impossible to reproduce physicochemical conditions in the solar nebula mainly because of the limited laboratory timescales. Therefore, each experimental work focuses on a single process or reproduction of certain mineralogical characteristics observed in meteorites and IDPs. The kinetically controlled reactions of abundant minerals such as forsterite were examined by laboratory experiments of evaporation, gas–solid reaction, and condensation. Evaporation and condensation coefficients were determined based on the Hertz–Knudsen equation and nucleation theory, which are important parameters controlling timescales of reaction, temperature dependences, grain size or reaction volume, and chemical fractionation occurring in a limited timescale. In addition, chemical compositions and textures of amorphous metastable materials were systematically investigated by condensation experiments of nanoparticles. Various types of laboratory experiments and theoretical studies are complementary to each other for understanding the mineralogy of extraterrestrial materials and dust formation and evolution in the solar nebula.

Subjects

  • Observational and Experimental Techniques
  • Small Bodies
  • Planet Formation

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