Revisiting the Relationship Between Rocky Exoplanet and Stellar Compositions: Reduced Evidence for a Super-Mercury Population
Planets and the stars they orbit are born from the same cloud of gas and dust, and the primordial compositions of rocky exoplanets have been assumed to have iron and refractory abundance ratios consistent with their host star. To test this assumption, we modeled the interior iron-to-rock ratio of 20...
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IOP Publishing
2024-01-01
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| Series: | The Astronomical Journal |
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| Online Access: | https://doi.org/10.3847/1538-3881/ad82eb |
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| author | Casey L. Brinkman Alex S. Polanski Daniel Huber Lauren M. Weiss Diana Valencia Mykhaylo Plotnykov |
| author_facet | Casey L. Brinkman Alex S. Polanski Daniel Huber Lauren M. Weiss Diana Valencia Mykhaylo Plotnykov |
| author_sort | Casey L. Brinkman |
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| description | Planets and the stars they orbit are born from the same cloud of gas and dust, and the primordial compositions of rocky exoplanets have been assumed to have iron and refractory abundance ratios consistent with their host star. To test this assumption, we modeled the interior iron-to-rock ratio of 20 super-Earth-sized (1–1.8 R _⊕ ) exoplanets around stars with homogeneously measured stellar parameters. We computed the core mass fraction (CMF) for each planet and an equivalent “core mass fraction” for each host star based on its Fe and Mg abundances. We then fit a linear correlation using two methods (ordinary least squares and orthogonal distance regression) between planetary and stellar CMF, obtaining substantially different slopes between these two methods ( m = 1.3 ± 1.0 and m = 5.6 ± 1.6, respectively). Additionally, we find that 75% of planets have a CMF consistent with their host star to within 1 σ , and do not identify a distinct population of high-density super-Mercuries. Overall, we conclude that current uncertainties in observational data and differences in modeling methods prevent definitive conclusions about the relationship between planet and host-star chemical compositions. |
| format | Article |
| id | doaj-art-7f6efed2986840ae9ffc6162650f1f8d |
| institution | Kabale University |
| issn | 1538-3881 |
| language | English |
| publishDate | 2024-01-01 |
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| series | The Astronomical Journal |
| spelling | doaj-art-7f6efed2986840ae9ffc6162650f1f8d2024-11-21T16:54:57ZengIOP PublishingThe Astronomical Journal1538-38812024-01-01168628110.3847/1538-3881/ad82ebRevisiting the Relationship Between Rocky Exoplanet and Stellar Compositions: Reduced Evidence for a Super-Mercury PopulationCasey L. Brinkman0https://orcid.org/0000-0002-4480-310XAlex S. Polanski1https://orcid.org/0000-0001-7047-8681Daniel Huber2https://orcid.org/0000-0001-8832-4488Lauren M. Weiss3https://orcid.org/0000-0002-3725-3058Diana Valencia4https://orcid.org/0000-0003-3993-4030Mykhaylo Plotnykov5https://orcid.org/0000-0002-9479-2744Institute for Astronomy, University of Hawai’i , 2680 Woodlawn Drive, Honolulu, HI 96822, USA ; clbrinkm@hawaii.eduDepartment of Physics and Astronomy, University of Kansas , Lawrence, KS 66045, USAInstitute for Astronomy, University of Hawai’i , 2680 Woodlawn Drive, Honolulu, HI 96822, USA ; clbrinkm@hawaii.edu; Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney , Sydney, NSW 2006, AustraliaDepartment of Physics and Astronomy, University of Notre Dame , Notre Dame, IN 46556, USACentre for Planetary Sciences, University of Toronto , 1265 Military Trail, Toronto, ON M1C 1A4, CanadaCentre for Planetary Sciences, University of Toronto , 1265 Military Trail, Toronto, ON M1C 1A4, CanadaPlanets and the stars they orbit are born from the same cloud of gas and dust, and the primordial compositions of rocky exoplanets have been assumed to have iron and refractory abundance ratios consistent with their host star. To test this assumption, we modeled the interior iron-to-rock ratio of 20 super-Earth-sized (1–1.8 R _⊕ ) exoplanets around stars with homogeneously measured stellar parameters. We computed the core mass fraction (CMF) for each planet and an equivalent “core mass fraction” for each host star based on its Fe and Mg abundances. We then fit a linear correlation using two methods (ordinary least squares and orthogonal distance regression) between planetary and stellar CMF, obtaining substantially different slopes between these two methods ( m = 1.3 ± 1.0 and m = 5.6 ± 1.6, respectively). Additionally, we find that 75% of planets have a CMF consistent with their host star to within 1 σ , and do not identify a distinct population of high-density super-Mercuries. Overall, we conclude that current uncertainties in observational data and differences in modeling methods prevent definitive conclusions about the relationship between planet and host-star chemical compositions.https://doi.org/10.3847/1538-3881/ad82ebExoplanet astronomyExtrasolar rocky planets |
| spellingShingle | Casey L. Brinkman Alex S. Polanski Daniel Huber Lauren M. Weiss Diana Valencia Mykhaylo Plotnykov Revisiting the Relationship Between Rocky Exoplanet and Stellar Compositions: Reduced Evidence for a Super-Mercury Population The Astronomical Journal Exoplanet astronomy Extrasolar rocky planets |
| title | Revisiting the Relationship Between Rocky Exoplanet and Stellar Compositions: Reduced Evidence for a Super-Mercury Population |
| title_full | Revisiting the Relationship Between Rocky Exoplanet and Stellar Compositions: Reduced Evidence for a Super-Mercury Population |
| title_fullStr | Revisiting the Relationship Between Rocky Exoplanet and Stellar Compositions: Reduced Evidence for a Super-Mercury Population |
| title_full_unstemmed | Revisiting the Relationship Between Rocky Exoplanet and Stellar Compositions: Reduced Evidence for a Super-Mercury Population |
| title_short | Revisiting the Relationship Between Rocky Exoplanet and Stellar Compositions: Reduced Evidence for a Super-Mercury Population |
| title_sort | revisiting the relationship between rocky exoplanet and stellar compositions reduced evidence for a super mercury population |
| topic | Exoplanet astronomy Extrasolar rocky planets |
| url | https://doi.org/10.3847/1538-3881/ad82eb |
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