A Framework for Quantifying the Degeneracies of Exoplanet Interior Compositions
Several transiting super-Earths are expected to be discovered in the coming few years. While tools to model the interior structure of transiting planets exist, inferences about the composition are fraught with ambiguities. We present a framework to quantify how much we can robustly infer about super...
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| Format: | Article |
| Language: | en_US |
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Institute of Physics Publishing
2012
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| Online Access: | http://hdl.handle.net/1721.1/74117 https://orcid.org/0000-0003-0638-3455 https://orcid.org/0000-0002-6892-6948 |
| _version_ | 1811092713708191744 |
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| author | Rogers, Leslie Anne Seager, Sara |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Rogers, Leslie Anne Seager, Sara |
| author_sort | Rogers, Leslie Anne |
| collection | MIT |
| description | Several transiting super-Earths are expected to be discovered in the coming few years. While tools to model the interior structure of transiting planets exist, inferences about the composition are fraught with ambiguities. We present a framework to quantify how much we can robustly infer about super-Earth and Neptune-size exoplanet interiors from radius and mass measurements. We introduce quaternary diagrams to illustrate the range of possible interior compositions for planets with four layers (iron core, silicate mantles, water layers, and H/He envelopes). We apply our model to CoRoT-7b, GJ 436b, and HAT-P-11b. Interpretation of planets with H/He envelopes is limited by the model uncertainty in the interior temperature, while for CoRoT-7b observational uncertainties dominate. We further find that our planet interior model sharpens the observational constraints on CoRoT-7b's mass and radius, assuming the planet does not contain significant amounts of water or gas. We show that the strength of the limits that can be placed on a super-Earth's composition depends on the planet's density; for similar observational uncertainties, high-density super-Mercuries allow the tightest composition constraints. Finally, we describe how techniques from Bayesian statistics can be used to take into account in a formal way the combined contributions of both theoretical and observational uncertainties to ambiguities in a planet's interior composition. On the whole, with only a mass and radius measurement an exact interior composition cannot be inferred for an exoplanet because the problem is highly underconstrained. Detailed quantitative ranges of plausible compositions, however, can be found. |
| first_indexed | 2024-09-23T15:22:57Z |
| format | Article |
| id | mit-1721.1/74117 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T15:22:57Z |
| publishDate | 2012 |
| publisher | Institute of Physics Publishing |
| record_format | dspace |
| spelling | mit-1721.1/741172022-10-02T02:32:47Z A Framework for Quantifying the Degeneracies of Exoplanet Interior Compositions Rogers, Leslie Anne Seager, Sara Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Massachusetts Institute of Technology. Department of Physics Rogers, Leslie Anne Seager, Sara Several transiting super-Earths are expected to be discovered in the coming few years. While tools to model the interior structure of transiting planets exist, inferences about the composition are fraught with ambiguities. We present a framework to quantify how much we can robustly infer about super-Earth and Neptune-size exoplanet interiors from radius and mass measurements. We introduce quaternary diagrams to illustrate the range of possible interior compositions for planets with four layers (iron core, silicate mantles, water layers, and H/He envelopes). We apply our model to CoRoT-7b, GJ 436b, and HAT-P-11b. Interpretation of planets with H/He envelopes is limited by the model uncertainty in the interior temperature, while for CoRoT-7b observational uncertainties dominate. We further find that our planet interior model sharpens the observational constraints on CoRoT-7b's mass and radius, assuming the planet does not contain significant amounts of water or gas. We show that the strength of the limits that can be placed on a super-Earth's composition depends on the planet's density; for similar observational uncertainties, high-density super-Mercuries allow the tightest composition constraints. Finally, we describe how techniques from Bayesian statistics can be used to take into account in a formal way the combined contributions of both theoretical and observational uncertainties to ambiguities in a planet's interior composition. On the whole, with only a mass and radius measurement an exact interior composition cannot be inferred for an exoplanet because the problem is highly underconstrained. Detailed quantitative ranges of plausible compositions, however, can be found. Natural Sciences and Engineering Research Council of Canada (NSERC) 2012-10-18T20:13:20Z 2012-10-18T20:13:20Z 2010-04 Article http://purl.org/eprint/type/JournalArticle 0004-637X 1538-4357 http://hdl.handle.net/1721.1/74117 Rogers, L. A., and S. Seager. “A FRAMEWORK FOR QUANTIFYING THE DEGENERACIES OF EXOPLANET INTERIOR COMPOSITIONS.” The Astrophysical Journal 712.2 (2010): 974–991. Web. © 2010 IOP Publishing. https://orcid.org/0000-0003-0638-3455 https://orcid.org/0000-0002-6892-6948 en_US http://dx.doi.org/ 10.1088/0004-637x/712/2/974 Astrophysical Journal Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf Institute of Physics Publishing IOP |
| spellingShingle | Rogers, Leslie Anne Seager, Sara A Framework for Quantifying the Degeneracies of Exoplanet Interior Compositions |
| title | A Framework for Quantifying the Degeneracies of Exoplanet Interior Compositions |
| title_full | A Framework for Quantifying the Degeneracies of Exoplanet Interior Compositions |
| title_fullStr | A Framework for Quantifying the Degeneracies of Exoplanet Interior Compositions |
| title_full_unstemmed | A Framework for Quantifying the Degeneracies of Exoplanet Interior Compositions |
| title_short | A Framework for Quantifying the Degeneracies of Exoplanet Interior Compositions |
| title_sort | framework for quantifying the degeneracies of exoplanet interior compositions |
| url | http://hdl.handle.net/1721.1/74117 https://orcid.org/0000-0003-0638-3455 https://orcid.org/0000-0002-6892-6948 |
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