The Value of K2 in Determining Interior Composition of Terrestrial Planets
Abstract
The composition of exoplanets is interesting for theoretical reasons and for possible implications of planet habitability. Currently, only the mass and radius are able to be used to estimate the composition of well-understood transiting exoplanets. With only these parameters to depend on, there is still significant uncertainty in the interior composition, as there are many possible interior compositions for a planet with a given mass and radius. Another observable parameter that could be used is k2, the planetary Love number, a measurement of the central condensation of a planet (equivalent to J2) that could be measurable in the future via repeated transit measurements (Ragozzine & Wolf 2009, Batygin et al. 2009). We have developed a program that calculates the k2 of planets from their interior density distribution by numerically integrating the Clairaut-Radau equation. The model has been applied to a large sample of terrestrial planets ranging from 0.5-8 Earth masses and 0.5-5 Earth radii. These sample planets have a wide variety of compositions iron, rock, ice, and gas (from Rodgers & Seager 2009 and Zeng & Seager 2008) to explore how k2 can be used to break the degeneracy of interior composition, even for model planets with well-known masses and radii (see also Kramm et al. 2011). We will present the value of k2 measurements in narrowing the range of possible interior structures of terrestrial planets. We will make the software that calculates k2 available for theorists to use in related studies of exoplanets.
- Publication:
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American Astronomical Society Meeting Abstracts #218
- Pub Date:
- May 2011
- Bibcode:
- 2011AAS...21812810M