Small planet radius gap
The small planet radius gap (also called the Fulton gap, photoevaporation valley, or Sub-Neptune Desert) is an observed scarcity of planets with radii between 1.5 and 2 times Earth's radius, likely due to photoevaporation-driven mass loss. A bimodality in the Kepler exoplanet population was first observed in 2013, and was noted as possibly confirming an emerging hypothesis that photoevaporation could drive atmospheric mass loss on close-in, low-mass planets. This would lead to a population of bare, rocky cores with smaller radii at small separations from their parent stars, and planets with thick hydrogen- and helium-dominated envelopes with larger radii at larger separations. The bimodality in the distribution was confirmed with higher-precision data in the California-Kepler Survey in 2017, which was shown to match the predictions of the photoevaporative mass-loss hypothesis later that year.
Despite the implication of the word 'gap', the Fulton gap does not actually represent a range of radii completely absent from the observed exoplanet population, but rather a range of radii that appear to be relatively uncommon. As a result, 'valley' is often used in place of 'gap'. The specific term "Fulton gap" is named for Benjamin J. Fulton, whose doctoral thesis included precision radius measurements that confirmed the scarcity of planets between 1.5 and 2 Earth radii, for which he won the Robert J. Trumpler Award, although the existence of this radius gap had been noted along with its underlying mechanisms as early as 2012 and 2013.
Other possible explanations
- Runaway gas accretion by larger planets.
- Observational bias favoring easier detection of hot ocean planets with extended steam atmospheres.
- Earth analog
- Planetary science
- Kepler space telescope
- Atmospheric escape
- Formation and evolution of the Solar System
- Boyle, Rebecca (2019-05-16). "As Planet Discoveries Pile Up, a Gap Appears in the Pattern". Quanta Magazine. Retrieved 2020-06-24.
- Van Eylen, V; Agentoft, Camilla; Lundkvist, M S; Kjeldsen, H; Owen, J E; Fulton, B J; Petigura, E; Snellen, I (2018-07-06). "An asteroseismic view of the radius valley: stripped cores, not born rocky". Monthly Notices of the Royal Astronomical Society. Oxford University Press (OUP). 479 (4): 4786–4795. arXiv:1710.05398. doi:10.1093/mnras/sty1783. ISSN 0035-8711.
- Armstrong, David J.; Meru, Farzana; Bayliss, Daniel; Kennedy, Grant M.; Veras, Dimitri (2019-07-17). "A Gap in the Mass Distribution for Warm Neptune and Terrestrial Planets". The Astrophysical Journal. American Astronomical Society. 880 (1): L1. doi:10.3847/2041-8213/ab2ba2. ISSN 2041-8213.
- McDonald, George D.; Kreidberg, Laura; Lopez, Eric (2019-04-29). "The Sub-Neptune Desert and Its Dependence on Stellar Type: Controlled by Lifetime X-Ray Irradiation". The Astrophysical Journal. American Astronomical Society. 876 (1): 22. doi:10.3847/1538-4357/ab1095. ISSN 1538-4357.
- Owen, James E.; Wu, Yanqin (2013-09-12). "KEPLERPLANETS: A TALE OF EVAPORATION". The Astrophysical Journal. IOP Publishing. 775 (2): 105. arXiv:1303.3899. doi:10.1088/0004-637x/775/2/105. ISSN 0004-637X.
- Fulton, Benjamin J.; Petigura, Erik A.; Howard, Andrew W.; Isaacson, Howard; Marcy, Geoffrey W.; Cargile, Phillip A.; Hebb, Leslie; Weiss, Lauren M.; Johnson, John Asher; Morton, Timothy D.; Sinukoff, Evan; Crossfield, Ian J. M.; Hirsch, Lea A. (2017-08-24). "The California-KeplerSurvey. III. A Gap in the Radius Distribution of Small Planets". The Astronomical Journal. American Astronomical Society. 154 (3): 109. arXiv:1703.10375. doi:10.3847/1538-3881/aa80eb. ISSN 1538-3881.
- Owen, James E.; Wu, Yanqin (2017-09-20). "The Evaporation Valley in the Kepler Planets". The Astrophysical Journal. American Astronomical Society. 847 (1): 29. arXiv:1705.10810. doi:10.3847/1538-4357/aa890a. ISSN 1538-4357.
- Lopez, Eric D.; Fortney, Jonathan J.; Miller, Neil (2012-11-21). "HOW THERMAL EVOLUTION AND MASS-LOSS SCULPT POPULATIONS OF SUPER-EARTHS AND SUB-NEPTUNES: APPLICATION TO THE KEPLER-11 SYSTEM AND BEYOND". The Astrophysical Journal. IOP Publishing. 761 (1): 59. doi:10.1088/0004-637x/761/1/59. ISSN 0004-637X.
- "BJ Fulton Wins 2018 Robert J. Trumpler Award for 'Landmark' Exoplanet Discovery Using Keck Observatory". W.M. Keck Observatory. 2018-09-10. Retrieved 2018-09-11.
- "IfA graduate receives prestigious award for work on extrasolar planets". University of Hawaiʻi System News. 2018-08-15. Retrieved 2018-09-11.
- Venturini, Julia; Helled, Ravit (17 October 2017). "The Formation of Mini-Neptunes". The Astrophysical Journal. 848 (2): 95. arXiv:1709.04736. Bibcode:2017ApJ...848...95V. doi:10.3847/1538-4357/aa8cd0.
- Mousis, Olivier; Deleuil, Magali; Aguichine, Artyom; Marcq, Emmanuel; Naar, Joseph; Lorena Acuña Aguirre; Brugger, Bastien; Goncalves, Thomas (2020). "Irradiated ocean planets bridge super-Earth and sub-Neptune populations". arXiv:2002.05243 [astro-ph.EP].
- Fulton, Benjamin J.; Petigura, Erik A.; Howard, Andrew W.; Isaacson, Howard; Marcy, Geoffrey W.; Cargile, Phillip A.; Hebb, Leslie; Weiss, Lauren M.; Johnson, John Asher; Morton, Timothy D.; Sinukoff, Evan; Crossfield, Ian J. M.; Hirsch, Lea A. (2017-08-24). "The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets". The Astronomical Journal. 154 (3): 109. arXiv:1703.10375. Bibcode:2017AJ....154..109F. doi:10.3847/1538-3881/aa80eb. ISSN 1538-3881.
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