Exoplanets & Exomoons

Planet Formation — Observational Constraints, Physical Processes, And Compositional Patterns

By Keith Cowing
Status Report
April 26, 2024
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Planet Formation — Observational Constraints, Physical Processes, And Compositional Patterns
This is an artist’s impression of a young star surrounded by a protoplanetary disc in which planets are forming. An international team of astronomers have used the NASA/ESA/CSA James Webb Space Telescope to provide the first observation of water and other molecules in the inner, rocky-planet-forming regions of a disc in one of the most extreme environments in our galaxy. These results suggest that the conditions for rocky-planet  formation, typically found in the discs of low-mass star-forming regions, can also occur in massive-star-forming regions and possibly a broader range of environments. [Image description: At the centre of the image, a bright light source illuminates a surrounding disc, which transitions from colours of white, grey, to orange. The disc is slightly tilted from upper left to lower right, and has spiral features that are most prominent near the star. Small, rocky objects are scattered throughout the disc. At upper right, there is a gap through which background stars can be seen.]

The goal of planet formation as a field of study is not only to provide the understanding of how planets come into existence.

It is also an interdisciplinary bridge which links astronomy to geology and mineralogy. Recent observations of young stars accompanied by their protoplanetary disks (Manara et al. 2022) provide direct insights into the conditions at which planets are forming.

These astronomical observations can be taken as initial conditions for the models of planet formation. In this chapter, we first give an brief overview of key observational constraints for planet formation theory derived from both the solar system and from the exoplanet population. We then review physical mechanisms governing planetary system formation and discuss how they can be put together to form global planet formation models.

Finally, we discuss how the compositional links from protoplanetary disks to planetary atmospheres put novel constraints on planet formation theory. In particular, we are currently gaining insights into the composition of the inner, planet-forming region within the disks thanks to observations from the James Webb Space Telescope (Grant et al. 2023; Perotti et al. 2023).

The task for planet formation modelling is then to link these observational properties and compositional content to the physical properties, and also the elementary inventory of meteorites, the Moon, Earth, and the other planets. If successful, this global approach can provide useful constraints for geological studies.

Christoph Mordasini, Remo Burn

Comments: Chapter 3 accepted for publication in the Reviews in Mineralogy and Geochemistry (RiMG) Volume 90 on “Exoplanets: Compositions, Mineralogy, and Evolution” edited by Natalie Hinkel, Keith Putirka, and Siyi Xu; 39 pages, 15 figures, and 39 equations
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR); Geophysics (physics.geo-ph)
Cite as: arXiv:2404.15555 [astro-ph.EP] (or arXiv:2404.15555v1 [astro-ph.EP] for this version)
Submission history
From: Christoph Mordasini [via Natalie Hinkel as proxy]
[v1] Tue, 23 Apr 2024 23:06:00 UTC (18,144 KB)


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