TRAPPIST-1e Has a Large Iron Core

Gabrielle Suissa, David Kipping
(Submitted on 26 Apr 2018)

The TRAPPIST-1 system provides an exquisite laboratory for understanding exoplanetary atmospheres and interiors. Their mutual gravitational interactions leads to transit timing variations, from which Grimm et al. (2018) recently measured the planetary masses with precisions ranging from 5% to 12%. Using these masses and the <5% radius measurements on each planet, we apply the method described in Suissa et al. (2018) to infer the minimum and maximum CRF (core radius fraction) of each planet. Further, we modify the maximum limit to account for the fact that a light volatile envelope is excluded for planets b through f. Only planet e is found to have a significant probability of having a non-zero minimum CRF, with a 0.7% false-alarm probability it has no core. Our method further allows us to measure the CRF of planet e to be greater than (49 +/- 7)% but less than (72 +/- 2)%, which is compatible with that of the Earth. TRAPPIST-1e therefore possess a large iron core similar to the Earth, in addition to being Earth-sized and located in the temperature zone. Comments:    Accepted to RNAAS, 2 pages, 1 figure
Subjects:    Earth and Planetary Astrophysics (astro-ph.EP)
Cite as:    arXiv:1804.10618 [astro-ph.EP] (or arXiv:1804.10618v1 [astro-ph.EP] for this version)
Submission history
From: Gabrielle Suissa 
[v1] Thu, 26 Apr 2018 18:05:00 GMT (6534kb,D)
https://arxiv.org/abs/1804.10618