The Nature and Origins of Sub‐Neptune Size Planets

Autor: Sean N. Raymond, Jacob L. Bean, James E. Owen
Přispěvatelé: Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Raymond, Sean, The Royal Society, Commission of the European Communities
Rok vydání: 2021
Předmět:
Geochemistry & Geophysics
Atmospheres
010504 meteorology & atmospheric sciences
[PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Planetary Atmospheres
Clouds
and Hazes
FOS: Physical sciences
Exoplanets: The Nexus of Astronomy and Geoscience
Atmospheric Composition and Structure
Review Article
01 natural sciences
Planetary Geochemistry
Protoplanetary nebula
Astrobiology
Planetary Sciences: Solar System Objects
Geochemistry and Petrology
Neptune
Planet
0201 Astronomical and Space Sciences
Earth and Planetary Sciences (miscellaneous)
0402 Geochemistry
Formation of Stars and Planets
Astrophysics::Solar and Stellar Astrophysics
Planetary Sciences: Astrobiology
Planetary Sciences: Solid Surface Planets
Planetary Sciences: Fluid Planets
Mineralogy and Petrology
0105 earth and related environmental sciences
Earth and Planetary Astrophysics (astro-ph.EP)
Physics
Science & Technology
Planetary Atmospheres
Photoevaporation
Exoplanet
Bimodality
Planetary Mineralogy and Petrology
[PHYS.ASTR.EP] Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]
Stars
Geochemistry
Geophysics
0403 Geology
13. Climate action
Space and Planetary Science
Physical Sciences
Terrestrial planet
Planetary Sciences: Comets and Small Bodies
Astrophysics::Earth and Planetary Astrophysics
Extra‐solar Planets
Composition
Astrophysics - Earth and Planetary Astrophysics
Zdroj: Journal of Geophysical Research. Planets
ISSN: 2169-9100
2169-9097
DOI: 10.1029/2020je006639
Popis: Planets intermediate in size between the Earth and Neptune, and orbiting closer to their host stars than Mercury does the Sun, are the most common type of planet revealed by exoplanet surveys over the last quarter century. Results from NASA's Kepler mission have revealed a bimodality in the radius distribution of these objects, with a relative underabundance of planets between 1.5 and 2.0 $R_{\oplus}$. This bimodality suggests that sub-Neptunes are mostly rocky planets that were born with primary atmospheres a few percent by mass accreted from the protoplanetary nebula. Planets above the radius gap were able to retain their atmospheres ("gas-rich super-Earths"), while planets below the radius gap lost their atmospheres and are stripped cores ("true super-Earths"). The mechanism that drives atmospheric loss for these planets remains an outstanding question, with photoevaporation and core-powered mass loss being the prime candidates. As with the mass-loss mechanism, there are two contenders for the origins of the solids in sub-Neptune planets: the migration model involves the growth and migration of embryos from beyond the ice line, while the drift model involves inward-drifting pebbles that coagulate to form planets close-in. Atmospheric studies have the potential to break degeneracies in interior structure models and place additional constraints on the origins of these planets. However, most atmospheric characterization efforts have been confounded by aerosols. Observations with upcoming facilities are expected to finally reveal the atmospheric compositions of these worlds, which are arguably the first fundamentally new type of planetary object identified from the study of exoplanets.
Comment: Invited review in press in JGR: Planets special edition on exoplanets
Databáze: OpenAIRE
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