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Title: 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 » simulations to demonstrate that many intermediate-size planets are “water worlds.”« less

Authors:
ORCiD logo; ; ; ; ; ; ORCiD logo; ; ; ; ; ; ; ORCiD logo; ;
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}
}

Journal Article:
Free Publicly Available Full Text
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DOI: 10.1073/pnas.1812905116

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Cited by: 15 works
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Works referenced in this record:

Spectrally resolved helium absorption from the extended atmosphere of a warm Neptune-mass exoplanet
journal, December 2018


Detection of He I λ10830 Å absorption on HD 189733 b with CARMENES high-resolution transmission spectroscopy
journal, December 2018


The NASA Exoplanet Archive: Data and Tools for Exoplanet Research
journal, August 2013

  • Akeson, R. L.; Chen, X.; Ciardi, D.
  • Publications of the Astronomical Society of the Pacific, Vol. 125, Issue 930
  • DOI: 10.1086/672273

Collisional Stripping and Disruption of Super-Earths
journal, July 2009


On the Snow Line in Dusty Protoplanetary Disks
journal, January 2000

  • Sasselov, D. D.; Lecar, M.
  • The Astrophysical Journal, Vol. 528, Issue 2
  • DOI: 10.1086/308209

Gaia Data Release 2 : Summary of the contents and survey properties
journal, August 2018


Planet-Planet Scattering Leads to Tightly Packed Planetary Systems
journal, April 2009


Gaia Data Release 2 : The astrometric solution
journal, August 2018


Imaging the water snow-line during a protostellar outburst
journal, July 2016

  • Cieza, Lucas A.; Casassus, Simon; Tobin, John
  • Nature, Vol. 535, Issue 7611
  • DOI: 10.1038/nature18612

On the water delivery to terrestrial embryos by ice pebble accretion
journal, April 2016


Revised Radii of Kepler Stars and Planets Using Gaia Data Release 2
journal, October 2018

  • Berger, Travis A.; Huber, Daniel; Gaidos, Eric
  • The Astrophysical Journal, Vol. 866, Issue 2
  • DOI: 10.3847/1538-4357/aada83

Miscibility Calculations for Water and Hydrogen in Giant Planets
journal, June 2015


Detection of Helium in the Atmosphere of the Exo-Neptune HAT-P-11b
journal, November 2018

  • Mansfield, Megan; Bean, Jacob L.; Oklopčić, Antonija
  • The Astrophysical Journal, Vol. 868, Issue 2
  • DOI: 10.3847/2041-8213/aaf166

The California- Kepler Survey. III. A Gap in the Radius Distribution of Small Planets
journal, August 2017

  • Fulton, Benjamin J.; Petigura, Erik A.; Howard, Andrew W.
  • The Astronomical Journal, Vol. 154, Issue 3
  • DOI: 10.3847/1538-3881/aa80eb

Compact Multi-planet Systems are more Common around Metal-poor Hosts
journal, October 2018

  • Brewer, John M.; Wang, Songhu; Fischer, Debra A.
  • The Astrophysical Journal, Vol. 867, Issue 1
  • DOI: 10.3847/2041-8213/aae710

Planetary Candidates Observed by Kepler . VIII. A Fully Automated Catalog with Measured Completeness and Reliability Based on Data Release 25
journal, April 2018

  • Thompson, Susan E.; Coughlin, Jeffrey L.; Hoffman, Kelsey
  • The Astrophysical Journal Supplement Series, Vol. 235, Issue 2
  • DOI: 10.3847/1538-4365/aab4f9

Ground-based detection of an extended helium atmosphere in the Saturn-mass exoplanet WASP-69b
journal, December 2018


Evidence for Water in the Rocky Debris of a Disrupted Extrasolar Minor Planet
journal, October 2013


Likely detection of water-rich asteroid debris in a metal-polluted white dwarf
journal, April 2015

  • Raddi, R.; Gänsicke, B. T.; Koester, D.
  • Monthly Notices of the Royal Astronomical Society, Vol. 450, Issue 2
  • DOI: 10.1093/mnras/stv701

The GRAINS thermodynamic and kinetic code for modeling nebular condensation
journal, June 2009


Rapid formation of Jupiter by diffusive redistribution of water vapor in the solar nebula
journal, July 1988


The ice composition in the disk around V883 Ori revealed by its stellar outburst
journal, February 2019


EVIDENCE FOR A SNOW LINE BEYOND THE TRANSITIONAL RADIUS IN THE TW Hya PROTOPLANETARY DISK
journal, March 2013


The great dichotomy of the Solar System: Small terrestrial embryos and massive giant planet cores
journal, September 2015


275 Candidates and 149 Validated Planets Orbiting Bright Stars in K 2 Campaigns 0–10
journal, March 2018

  • Mayo, Andrew W.; Vanderburg, Andrew; Latham, David W.
  • The Astronomical Journal, Vol. 155, Issue 3
  • DOI: 10.3847/1538-3881/aaadff

Structure of the Solar Nebula, Growth and Decay of Magnetic Fields and Effects of Magnetic and Turbulent Viscosities on the Nebula
journal, January 1981

  • Hayashi, Chushiro
  • Progress of Theoretical Physics Supplement, Vol. 70
  • DOI: 10.1143/PTPS.70.35

Forming Planets via Pebble Accretion
journal, August 2017


The California- Kepler Survey. IV. Metal-rich Stars Host a Greater Diversity of Planets
journal, January 2018

  • Petigura, Erik A.; Marcy, Geoffrey W.; Winn, Joshua N.
  • The Astronomical Journal, Vol. 155, Issue 2
  • DOI: 10.3847/1538-3881/aaa54c

The formation of super-Earths and mini-Neptunes with giant impacts
journal, February 2015

  • Inamdar, Niraj K.; Schlichting, Hilke E.
  • Monthly Notices of the Royal Astronomical Society, Vol. 448, Issue 2
  • DOI: 10.1093/mnras/stv030

H-atmospheres of Icy Super-Earths Formed In Situ in the Outer Solar System: An Application to a Possible Planet Nine
journal, April 2017


Mass Distribution and Planet Formation in the Solar Nebula
journal, December 2007

  • Desch, S. J.
  • The Astrophysical Journal, Vol. 671, Issue 1
  • DOI: 10.1086/522825

A Detailed Model Grid for Solid Planets from 0.1 through 100 Earth Masses
journal, March 2013

  • Zeng, Li; Sasselov, Dimitar
  • Publications of the Astronomical Society of the Pacific, Vol. 125, Issue 925
  • DOI: 10.1086/669163

Mass–Radius Relation for Rocky Planets Based on prem
journal, March 2016


Atmospheres of Protoplanetary Cores: Critical Mass for Nucleated Instability
journal, September 2006

  • Rafikov, Roman R.
  • The Astrophysical Journal, Vol. 648, Issue 1
  • DOI: 10.1086/505695

The discoveries of WASP-91b, WASP-105b and WASP-107b: Two warm Jupiters and a planet in the transition region between ice giants and gas giants
journal, August 2017


The Evaporation Valley in the Kepler Planets
journal, September 2017


C/O and Snowline Locations in Protoplanetary Disks: the Effect of Radial Drift and Viscous gas Accretion
journal, December 2015

  • Piso, Ana-Maria A.; Öberg, Karin I.; Birnstiel, Tilman
  • The Astrophysical Journal, Vol. 815, Issue 2
  • DOI: 10.1088/0004-637X/815/2/109

Volatile Transport Inside Super-Earths by Entrapment in the Water-Ice Matrix
journal, May 2013


Consequences of Giant Impacts on Early Uranus for Rotation, Internal Structure, Debris, and Atmospheric Erosion
journal, July 2018

  • Kegerreis, J. A.; Teodoro, L. F. A.; Eke, V. R.
  • The Astrophysical Journal, Vol. 861, Issue 1
  • DOI: 10.3847/1538-4357/aac725

Evidence of fast Pebble Growth near Condensation Fronts in the hl tau Protoplanetary disk
journal, June 2015


Empirical Accurate Masses and Radii of Single Stars with TESS and Gaia
journal, December 2017

  • Stassun, Keivan G.; Corsaro, Enrico; Pepper, Joshua A.
  • The Astronomical Journal, Vol. 155, Issue 1
  • DOI: 10.3847/1538-3881/aa998a

Experimental evidence for superionic water ice using shock compression
journal, February 2018


An asteroseismic view of the radius valley: stripped cores, not born rocky
journal, July 2018

  • Van Eylen, V.; Agentoft, Camilla; Lundkvist, M. S.
  • Monthly Notices of the Royal Astronomical Society, Vol. 479, Issue 4
  • DOI: 10.1093/mnras/sty1783

The California- Kepler Survey. VII. Precise Planet Radii Leveraging Gaia DR2 Reveal the Stellar Mass Dependence of the Planet Radius Gap
journal, November 2018


Survival function analysis of planet size distribution with Gaia Data Release 2 updates
journal, July 2018

  • Zeng, Li; Jacobsen, Stein B.; Sasselov, Dimitar D.
  • Monthly Notices of the Royal Astronomical Society, Vol. 479, Issue 4
  • DOI: 10.1093/mnras/sty1749

C/O AND Mg/Si RATIOS OF STARS IN THE SOLAR NEIGHBORHOOD
journal, October 2016


On the evolution of the snow line in protoplanetary discs: Evolution of the snow line
journal, July 2012


Low temperature condensation from the solar nebula
journal, April 1972


The Complete Transmission Spectrum of WASP-39b with a Precise Water Constraint
journal, December 2017


STRUCTURE AND DYNAMICS OF COLD WATER SUPER-EARTHS: THE CASE OF OCCLUDED CH 4 AND ITS OUTGASSING
journal, August 2014


The Exoplanet Mass-Ratio Function from the Moa-Ii Survey: Discovery of a Break and Likely peak at a Neptune mass
journal, December 2016


The Effects of Snowlines on c/o in Planetary Atmospheres
journal, November 2011


Helium in the eroding atmosphere of an exoplanet
journal, May 2018


WFIRST Exoplanet Mass-measurement Method Finds a Planetary Mass of 39 ± 8 M for OGLE-2012-BLG-0950Lb
journal, November 2018

  • Bhattacharya, A.; Beaulieu, J. -P.; Bennett, D. P.
  • The Astronomical Journal, Vol. 156, Issue 6
  • DOI: 10.3847/1538-3881/aaed46

Planet-Disk Interaction and Orbital Evolution
journal, September 2012


Ocean Planet or Thick Atmosphere: On the Mass‐Radius Relationship for Solid Exoplanets with Massive Atmospheres
journal, February 2008

  • Adams, E. R.; Seager, S.; Elkins‐Tanton, L.
  • The Astrophysical Journal, Vol. 673, Issue 2
  • DOI: 10.1086/524925

HELIUM ATMOSPHERES ON WARM NEPTUNE- AND SUB-NEPTUNE-SIZED EXOPLANETS AND APPLICATIONS TO GJ 436b
journal, June 2015