Radius and Structure Models of the First Super-Earth Planet

By D. Valencia, D. Sasselov, R. O’Connell. 2006

209 citations recorded by the source corpus.

With improving methods and surveys, the young field of extrasolar planet studies has recently expanded into a qualitatively new domain—terrestrial (mostly rocky) planets. The first such planets were discovered during the past year and a half, judging by their measured masses of less than 10 M⊕ ("super-Earths"). They are introducing a novel physical regime that has not been explored before, as such planets do not exist in our solar system. Their compositions can be completely terrestrial, or they may harbor an extensive ocean (water and ices) above a rocky core. We model the structure and properties of the first super-Earth (mass ~7.5 M⊕), discovered in 2005, illustrating the possible compositions and providing radius evaluations in view of future detection of similar planets by transits. We find that there exists a threshold in radius above which a super-Earth most certainly has an extensive water content. In the case of GJ 876d, this threshold is at about 12,000 km. Our results show that unique characterization of the bulk composition of super-Earths will be possible with future transit studies.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/184232fb0334821c88ddf235db350c0706a748b2

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In Astronomy and Astrophysics

1. Jon Fortney
2. Sara Seager
3. D. Charbonneau
4. G. Marcy
5. J. Winn
6. Timothy Morton
7. C. Mordasini
8. J. Johnson

In Instrumentation

1. D. Charbonneau
2. Jon Fortney
3. Sara Seager
4. J. Winn
5. G. Marcy
6. J. Southworth
7. Timothy Morton
8. C. Mordasini

Citations in the corpus

• THE LICK-CARNEGIE EXOPLANET SURVEY: A URANUS-MASS FOURTH PLANET FOR GJ 876 IN AN EXTRASOLAR LAPLACE CONFIGURATION (2010, background): “Even interior structure models of GJ 876 d have been introduced (Valencia et al. 2007).”
• Can we constrain the interior structure of rocky exoplanets from mass and radius measurements (2015, background): “For example, Valencia et al. (2006, 2007c); Sotin et al. (2007); Wagner et al. (2011) it has been shown that different core sizes and mantle compositions affect the mass-radius relationship, but to our knowledge no comprehensive study of the degeneracy of these model parameters has been performed.”
• Design Considerations for a Ground-Based Transit Search for Habitable Planets Orbiting M Dwarfs (2007, background): “…challenge to find a transiting planet in this mass regime; simply obtaining a radius measurement for such a planet (for which there are no Solar System analogs) would be extremely fruitful as it might allow one to distinguish between rocky or ocean planet composition models (Valencia et al. 2007).”
• Detailed Models of Super-Earths: How Well Can We Infer Bulk Properties? (2007, methodology): “…determine the total radius and interior distribution of bulk parameters (mass, gravity, pressure, and temperature) of terrestrial and ocean exoplanets (Valencia et al. 2006, 2007), and here we present another useful application of this model: how to obtain constraints on with values of M and R. 2.”
• Tidal Heating of Extrasolar Planets (2008, background): “To put these numbers in context, consider the geophysical modeling of this planet by Valencia et al. (2007b), who report that 7 ; 1017 Wwould be adequate to induce substantial internal melting of the mantle.”
• Mass-Radius Relationships for Solid Exoplanets (2007, methodology): “Some authors have stated or shown with models that temperature is not important for deriving a planet’s total mass and radius (see e.g., Valencia et al. 2006, 2007b; Fortney et al. 2007; Sotin et al. 2007, and references therein).”
• MODELING KEPLER TRANSIT LIGHT CURVES AS FALSE POSITIVES: REJECTION OF BLEND SCENARIOS FOR KEPLER-9, AND VALIDATION OF KEPLER-9 d, A SUPER-EARTH-SIZE PLANET IN A MULTIPLE SYSTEM (2010, methodology): “Approximate planetary radii were inferred from the masses using the structure models of Valencia et al. (2007), by drawing masses at random and assigning radii over the full range of compositions allowed by these models.”
• Compositional Imprints in Density–Distance–Time: A Rocky Composition for Close-in Low-mass Exoplanets from the Location of the Valley of Evaporation (2017, methodology): “Such combined measurements directly lead to the mean density of the planet which can be used as a first constraint on the bulk composition (e.g., Valencia et al. 2007, 2010; Rogers & Seager 2010b,a).”
• Mantle dynamics in super-Earths: Post-perovskite rheology and self-regulation of viscosity (2012, background): “This is consistent with predictions 566   from parameterised (Valencia and O'Connell, 2009; Valencia et al., 2007a) and simplified 567   numerical (Korenaga, 2010a; van Heck and Tackley, 2011) studies.”
• A Detailed Model Grid for Solid Planets from 0.1 through 100 Earth Masses (2013, background): “All the combinations together form a curve segment on the ternary diagram of Fe, MgSiO3 and H2O mass fractions (Zeng & Seager 2008; Valencia et al. 2007a).”
• HOW ROCKY ARE THEY? THE COMPOSITION DISTRIBUTION OF KEPLER’S SUB-NEPTUNE PLANET CANDIDATES WITHIN 0.15 AU (2014, background): “…exoNeptunes (Rogers et al. 2011), and scaling relations between mass and radius for sub-Jovian planets of varying compositions, including iron, silicates, water ice, carbon compounds, hydrogen/helium, and various combinations thereof (Valencia et al. 2006; Seager et al. 2007; Fortney et al. 2007).”
• THE COMPOSITIONAL DIVERSITY OF EXTRASOLAR TERRESTRIAL PLANETS. I. IN SITU SIMULATIONS (2010, background): “These results are also key for super Earth studies such as that of Valencia et al. (2007) and O’Neill et al. (2007).”
• MASS–RADIUS RELATION FOR ROCKY PLANETS BASED ON PREM (2015, background): “7] (3) For comparison, this semi-empirical mass-radius formula is in agreement with the mass- radius relation of super-Earths presented in Valencia et al. (2006), which is a scaling law of R ∝ M0.”
• Composition and fate of short-period super-Earths: The case of CoRoT-7b (2009, unknown): “For the solid/liquid regions we use a 3 layer (iron/rock/ice) hydrostatic model based on Vinet and shock equations of states; each layer is assumed to be isentropic except for the conductive thermal boundary layers at the top and bottom of the mantle (Valencia et al., 2006, 2007b).”