Detailed Models of Super-Earths: How Well Can We Infer Bulk Properties?

By D. Valencia, D. Sasselov, R. O’Connell. 2007

269 citations recorded by the source corpus.

The field of extrasolar planets has rapidly expanded to include the detection of planets with masses smaller than that of Uranus. Many of these are expected to have little or no hydrogen and helium gas, and we might find Earth analogs among them. In this paper we describe our detailed interior models for a rich variety of such massive terrestrial and ocean planets in the 1-10 M⊕ range (super-Earths). The grid presented here allows the characterization of the bulk composition of super-Earths detected in transit and with a measured mass. We show that, on average, planet radius measurements to better than 5%, combined with mass measurements to better than 10%, would permit us to distinguish between an icy or rocky composition. This is due to the fact that there is a maximum radius a rocky terrestrial planet may achieve for a given mass. Any value of the radius above this maximum terrestrial radius implies that the planet contains a large (>10%) amount of water (ocean planet).

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/af660b71def58656de22c634c61245d5f3da6b2e

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In Astronomy and Astrophysics

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

Citations in the corpus

• 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).”
• THE ATMOSPHERIC SIGNATURES OF SUPER-EARTHS: HOW TO DISTINGUISH BETWEEN HYDROGEN-RICH AND HYDROGEN-POOR ATMOSPHERES (2008, methodology): “Even the simple statistical distribution of very water-rich versus dry super-Earths in an observed sample would be sufficient (Valencia et al. 2007).”
• HUBBLE SPACE TELESCOPE NEAR-IR TRANSMISSION SPECTROSCOPY OF THE SUPER-EARTH HD 97658B (2014, background): “…sample it is possible to match their measured densities with a broad range of compositions, including both waterrich and water-poor scenarios, simply by varying the amount of hydrogen in their atmospheres (Seager et al. 2007; Valencia et al. 2007, 2013; Rogers & Seager 2010a; Zeng & Sasselov 2013).”
• Inevitability of Plate Tectonics on Super-Earths (2007, methodology): “We use detailed models of the internal structure of massive terrestrial planets (Valencia et al. 2006, 2007) and parameterized convection models to show that the condition for deformation and subsequent subduction is easily met by planets more massive than Earth.”
• Mass-Radius Relationships for Solid Exoplanets (2007, background): “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).”
• MASS–RADIUS RELATION FOR ROCKY PLANETS BASED ON PREM (2015, background): “…in the Super-Earth domain are based largely on experience (and extrapolations) from the models of the rocky solar system planets, and mostly - the Earth (Valencia et al. 2006, 2007b,a; Fortney et al. 2007; Seager et al. 2007; Zeng & Seager 2008; Grasset et al. 2009; Zeng & Sasselov 2013).”
• BULK COMPOSITION OF GJ 1214b AND OTHER SUB-NEPTUNE EXOPLANETS (2013, background): “…to the one that arises from trade-offs between three or more compositional end-members with different molecular weights – iron cores, silicate mantles, water/icy envelopes or oceans, H/He envelopes, which has been readily identified (Valencia et al. 2007; Adams et al. 2008; Rogers & Seager 2010a).”
• 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).”
• AN ANCIENT EXTRASOLAR SYSTEM WITH FIVE SUB-EARTH-SIZE PLANETS (2015, background): “In particular, α elements comprise the bulk of the material that constitutes rocky, Earth-size planets (Valencia et al. 2007, 2010).”
• DETECTION OF AN ATMOSPHERE AROUND THE SUPER-EARTH 55 CANCRI E (2015, background): “Even basic information about their density seems to suggest that there is a variety of cases (e.g. Sotin et al. 2007; Grasset et al. 2009; Valencia et al. 2007, 2013; Zeng & Sasselov 2014).”
• MOST 1.6 EARTH-RADIUS PLANETS ARE NOT ROCKY (2014, background): “Further, metallic iron and silicates have similar condensation temperatures in the protoplanetary disk (e.g., Petaev & Wood 2005), and are expected to concomitantly condense to form solids and to contribute together to the bulk material forming a rocky planet (Valencia et al. 2007).”
• UNDERSTANDING THE MASS–RADIUS RELATION FOR SUB-NEPTUNES: RADIUS AS A PROXY FOR COMPOSITION (2013, background): “For 1- 2 R⊕ planets the densities of water, silicate rocks, and iron (i.e. ∼ 1-10 gcm−3) are similar enough that it is impossible to uniquely constrain the relative abundance of these components (Valencia et al. 2007; Rogers & Seager 2010a).”
• HOW ROCKY ARE THEY? THE COMPOSITION DISTRIBUTION OF KEPLER’S SUB-NEPTUNE PLANET CANDIDATES WITHIN 0.15 AU (2014, methodology): “These models have been applied to numerous individual Neptunes and sub-Neptunes, such as GJ 876d (Valencia et al. 2007), CoRoT-7b (e.g. Léger et al. 2009; Valencia et al. 2010; Jackson et al. 2010), GJ1214b (e.g. Charbonneau et al. 2009; Rogers & Seager 2010; Nettelmann et al. 2011; Valencia et…”
• Characterization of the K2-18 multi-planetary system with HARPS: A habitable zone super-Earth and discovery of a second, warm super-Earth on a non-coplanar orbit (2017, background): “The planet is therefore likely too large to be a terrestrial Earth-like planet (Valencia et al. 2007; Fulton et al. 2017).”
• A Decreased Probability of Habitable Planet Formation around Low-Mass Stars (2007, background): “If any of the Gl 581 planets were to transit the parent star, then it would be possible to derive a rough composition (rocky vs. icy: Valencia et al. 2007; Fortney et al. 2007; Sotin et al. 2007), and to distinguish between these two formation scenarios (Gaidos et al. 2007; S. Raymond et al. 2007,…”