Architectures of Compact Multi-planet Systems: Diversity and Uniformity

Fuente: arXiv
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Autores principales: Weiss, Lauren M., Millholland, Sarah C., Petigura, Erik A., Adams, Fred C., Batygin, Konstantin, Bloch, Anthony M., Mordasini, Christoph
Formato: Preprint
Publicado: 2022
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author Weiss, Lauren M.
Millholland, Sarah C.
Petigura, Erik A.
Adams, Fred C.
Batygin, Konstantin
Bloch, Anthony M.
Mordasini, Christoph
author_facet Weiss, Lauren M.
Millholland, Sarah C.
Petigura, Erik A.
Adams, Fred C.
Batygin, Konstantin
Bloch, Anthony M.
Mordasini, Christoph
contents One of the most important developments in exoplanet science in the past decade is the discovery of multi-planet systems with sub-Neptune-sized planets interior to 1~AU. This chapter explores the architectures of these planetary systems, which often display a remarkable degree of uniformity: the planets have nearly equal sizes, regular orbital spacing, low eccentricities, and small mutual inclinations. This uniformity stands in sharp contrast to the diverse nature of the exoplanet sample considered as a whole (as well as our inner solar system). We begin with a critical review of the observations -- including possible biases -- and find that these peas-in-a-pod planetary systems are apparently a common outcome of the planet formation process. Modest departures from exact uniformity suggest additional patterns, such as the planet mass slowly increasing with semi-major axis. The star formation process naturally produces circumstellar disks with the properties required to produce these planetary systems, although the solid material must move inward from its initial location. We discuss primary modes of planetary assembly, the role of orbital migration, and post-nebular atmospheric loss. Mature planetary systems are found to be near their minimum energy (tidal equilibrium) configurations; this finding provides a partial explanation for their observed properties and indicates that efficient energy dissipation must occur. Finally, we consider population synthesis models and show that peas-in-a-pod patterns emerge with reasonable choices for the input parameters. Nonetheless, interesting observational and theoretical challenges remain in order to understand how these surprisingly organized planetary systems arise from the disorder of their formation processes.
format Preprint
id arxiv_https___arxiv_org_abs_2203_10076
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Architectures of Compact Multi-planet Systems: Diversity and Uniformity
Weiss, Lauren M.
Millholland, Sarah C.
Petigura, Erik A.
Adams, Fred C.
Batygin, Konstantin
Bloch, Anthony M.
Mordasini, Christoph
Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
One of the most important developments in exoplanet science in the past decade is the discovery of multi-planet systems with sub-Neptune-sized planets interior to 1~AU. This chapter explores the architectures of these planetary systems, which often display a remarkable degree of uniformity: the planets have nearly equal sizes, regular orbital spacing, low eccentricities, and small mutual inclinations. This uniformity stands in sharp contrast to the diverse nature of the exoplanet sample considered as a whole (as well as our inner solar system). We begin with a critical review of the observations -- including possible biases -- and find that these peas-in-a-pod planetary systems are apparently a common outcome of the planet formation process. Modest departures from exact uniformity suggest additional patterns, such as the planet mass slowly increasing with semi-major axis. The star formation process naturally produces circumstellar disks with the properties required to produce these planetary systems, although the solid material must move inward from its initial location. We discuss primary modes of planetary assembly, the role of orbital migration, and post-nebular atmospheric loss. Mature planetary systems are found to be near their minimum energy (tidal equilibrium) configurations; this finding provides a partial explanation for their observed properties and indicates that efficient energy dissipation must occur. Finally, we consider population synthesis models and show that peas-in-a-pod patterns emerge with reasonable choices for the input parameters. Nonetheless, interesting observational and theoretical challenges remain in order to understand how these surprisingly organized planetary systems arise from the disorder of their formation processes.
title Architectures of Compact Multi-planet Systems: Diversity and Uniformity
topic Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2203.10076