Two empirical regimes of the planetary mass-radius relation

Bashi, Dolev; Helled, Ravit; Zucker, Shay; Mordasini, Christoph (2017). Two empirical regimes of the planetary mass-radius relation. Astronomy and astrophysics, 604(A83), A83. EDP Sciences 10.1051/0004-6361/201629922

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Today, with the large number of detected exoplanets and improved measurements, we can reach the next step of planetary characterization. Classifying different populations of planets is not only important for our understanding of the demographics of various planetary types in the galaxy, but also for our understanding of planet formation. We explore the nature of two regimes in the planetary mass-radius (M-R) relation. We suggest that the transition between the two regimes of “small” and “large” planets occurs at a mass of 124 ± 7M⊕ and a radius of 12.1 ± 0.5R⊕. Furthermore, the M-R relation is R ∝ M0.55 ± 0.02 and R ∝ M0.01 ± 0.02 for small and large planets, respectively. We suggest that the location of the breakpoint is linked to the onset of electron degeneracy in hydrogen, and therefore to the planetary bulk composition. Specifically, it is the characteristic minimal mass of a planet that consists of mostly hydrogen and helium, and therefore its M-R relation is determined by the equation of state of these materials. We compare the M-R relation from observational data with the relation derived by population synthesis calculations and show that there is a good qualitative agreement between the two samples.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences > Theoretical Astrophysics and Planetary Science (TAPS)
08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences
08 Faculty of Science > Physics Institute
08 Faculty of Science > Physics Institute > NCCR PlanetS

UniBE Contributor:

Mordasini, Christoph

Subjects:

500 Science > 520 Astronomy
600 Technology > 620 Engineering
500 Science
500 Science > 530 Physics

ISSN:

0004-6361

Publisher:

EDP Sciences

Language:

English

Submitter:

Janine Jungo

Date Deposited:

20 Apr 2018 10:24

Last Modified:

22 Apr 2018 02:22

Publisher DOI:

10.1051/0004-6361/201629922

BORIS DOI:

10.7892/boris.112684

URI:

https://boris.unibe.ch/id/eprint/112684

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