Growth model interpretation of planet size distribution
Abstract
The radii and orbital periods of 4,000+ confirmed/candidate exoplanets have been precisely measured by the Kepler mission. The radii show a bimodal distribution, with two peaks corresponding to smaller planets (likely rocky) and larger intermediate-size planets, respectively. While only the masses of the planets orbiting the brightest stars can be determined by ground-based spectroscopic observations, these observations allow calculation of their average densities placing constraints on the bulk compositions and internal structures. However, an important question about the composition of planets ranging from 2 to 4 Earth radii (R ⊕ ) still remains. They may either have a rocky core enveloped in a H 2 –He gaseous envelope (gas dwarfs) or contain a significant amount of multicomponent, H 2 O-dominated ices/fluids (water worlds). Planets in the mass range of 10–15 M ⊕ , if half-ice and half-rock by mass, have radii of 2.5 R ⊕ , which exactly match the second peak of the exoplanet radius bimodal distribution. Any planet in the 2- to 4-R ⊕ range requires a gas envelope of at most a few mass percentage points, regardless of the core composition. To resolve the ambiguity of internal compositions, we use a growth model and conduct Monte Carlomore »
- Publication Date:
- Sponsoring Org.:
- USDOE
- OSTI Identifier:
- 1509918
- Grant/Contract Number:
- NA0001804; NA0002937; NA-0003525
- Resource Type:
- Published Article
- Journal Name:
- Proceedings of the National Academy of Sciences of the United States of America
- Additional Journal Information:
- Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Volume: 116 Journal Issue: 20; Journal ID: ISSN 0027-8424
- Publisher:
- Proceedings of the National Academy of Sciences
- Country of Publication:
- United States
- Language:
- English
Citation Formats
Zeng, Li, Jacobsen, Stein B., Sasselov, Dimitar D., Petaev, Michail I., Vanderburg, Andrew, Lopez-Morales, Mercedes, Perez-Mercader, Juan, Mattsson, Thomas R., Li, Gongjie, Heising, Matthew Z., Bonomo, Aldo S., Damasso, Mario, Berger, Travis A., Cao, Hao, Levi, Amit, and Wordsworth, Robin D. Growth model interpretation of planet size distribution. United States: N. p., 2019.
Web. doi:10.1073/pnas.1812905116.
Zeng, Li, Jacobsen, Stein B., Sasselov, Dimitar D., Petaev, Michail I., Vanderburg, Andrew, Lopez-Morales, Mercedes, Perez-Mercader, Juan, Mattsson, Thomas R., Li, Gongjie, Heising, Matthew Z., Bonomo, Aldo S., Damasso, Mario, Berger, Travis A., Cao, Hao, Levi, Amit, & Wordsworth, Robin D. Growth model interpretation of planet size distribution. United States. doi:10.1073/pnas.1812905116.
Zeng, Li, Jacobsen, Stein B., Sasselov, Dimitar D., Petaev, Michail I., Vanderburg, Andrew, Lopez-Morales, Mercedes, Perez-Mercader, Juan, Mattsson, Thomas R., Li, Gongjie, Heising, Matthew Z., Bonomo, Aldo S., Damasso, Mario, Berger, Travis A., Cao, Hao, Levi, Amit, and Wordsworth, Robin D. Mon .
"Growth model interpretation of planet size distribution". United States. doi:10.1073/pnas.1812905116.
@article{osti_1509918,
title = {Growth model interpretation of planet size distribution},
author = {Zeng, Li and Jacobsen, Stein B. and Sasselov, Dimitar D. and Petaev, Michail I. and Vanderburg, Andrew and Lopez-Morales, Mercedes and Perez-Mercader, Juan and Mattsson, Thomas R. and Li, Gongjie and Heising, Matthew Z. and Bonomo, Aldo S. and Damasso, Mario and Berger, Travis A. and Cao, Hao and Levi, Amit and Wordsworth, Robin D.},
abstractNote = {The radii and orbital periods of 4,000+ confirmed/candidate exoplanets have been precisely measured by the Kepler mission. The radii show a bimodal distribution, with two peaks corresponding to smaller planets (likely rocky) and larger intermediate-size planets, respectively. While only the masses of the planets orbiting the brightest stars can be determined by ground-based spectroscopic observations, these observations allow calculation of their average densities placing constraints on the bulk compositions and internal structures. However, an important question about the composition of planets ranging from 2 to 4 Earth radii (R ⊕ ) still remains. They may either have a rocky core enveloped in a H 2 –He gaseous envelope (gas dwarfs) or contain a significant amount of multicomponent, H 2 O-dominated ices/fluids (water worlds). Planets in the mass range of 10–15 M ⊕ , if half-ice and half-rock by mass, have radii of 2.5 R ⊕ , which exactly match the second peak of the exoplanet radius bimodal distribution. Any planet in the 2- to 4-R ⊕ range requires a gas envelope of at most a few mass percentage points, regardless of the core composition. To resolve the ambiguity of internal compositions, we use a growth model and conduct Monte Carlo simulations to demonstrate that many intermediate-size planets are “water worlds.”},
doi = {10.1073/pnas.1812905116},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
number = 20,
volume = 116,
place = {United States},
year = {2019},
month = {4}
}
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DOI: 10.1073/pnas.1812905116
DOI: 10.1073/pnas.1812905116
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