A compositional link between rocky exoplanets and their host stars.
Vardan Adibekyan1,2, Caroline Dorn3, Sérgio G Sousa1
1Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, Centro de Astrofísica da Universidade do Porto, 4150-762 Porto, Portugal.
Researchers found a compositional link between rocky exoplanets and their host stars, suggesting planet formation processes influence planetary composition. Super-Earths and super-Mercuries show distinct compositions, indicating different formation pathways.
Area of Science:
- Astronomy and Astrophysics
- Exoplanetary Science
- Planetary Formation
Background:
- Stars and planets accrete material from a common protoplanetary disk.
- Theoretical models predict a relationship between the bulk compositions of stars and their planets.
- Understanding this relationship is key to deciphering planet formation processes.
Purpose of the Study:
- To investigate the compositional link between rocky exoplanets and their host stars.
- To determine if exoplanet composition reflects the composition of their formation disk.
- To explore potential differences in formation pathways for distinct planet types.
Main Methods:
- Estimating the iron-mass fraction of rocky exoplanets using their measured masses and radii.
- Comparing exoplanet iron-mass fractions with the compositions of their host stars.
- Assuming host star composition represents the protoplanetary disk composition.
Main Results:
- A significant positive correlation was found between exoplanet iron-mass fraction and host star composition.
- The observed correlation exhibits a slope greater than 4, deviating from a 1:1 relationship.
- Distinct compositional differences were identified between Super-Earths and super-Mercuries.
Conclusions:
- The findings support a connection between planet and host star composition, influenced by planet formation.
- The observed correlation suggests that planet formation processes preferentially enrich planets in iron.
- The distinct compositions of Super-Earths and super-Mercuries imply divergent formation histories.
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