Definition
Extrasolar planets with relatively low masses (below ~20–30 M⊕) show a wide range of bulk densities. This hints at a great compositional diversity, with planet classes that do not exist in the Solar System such as ➝ Super-Earths and ➝ Mini-Neptunes (Jontof-Hutter 2019; Spiegel et al. 2014). Models of the ➝ interior structure describe the hydrostatic and thermodynamic state of these planets. They provide radial distributions of density, pressure, temperature, and composition consistent with given mass and radius measurements. Due to the lack of observable planetary properties, interior structure models are often underconstrained and thus subject to large inherent degeneracies. Finding ways to break these degeneracies is a major goal in exoplanetary science.
Overview
In the ➝ Solar System, a wealth of information about the interiors of the planets is available from direct observations, space probes, and in situ measurements, which helps building a rather comprehensive picture...
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References and Further Reading
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Baumeister, P., Tosi, N. (2022). Interior Structure of Low-Mass Exoplanets. In: Gargaud, M., et al. Encyclopedia of Astrobiology. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-27833-4_5608-1
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