NASA | JPL-Caltech | 2021 Jan 22
Precise measurements reveal that the exoplanets have remarkably similar densities, which provides clues about their composition.
The red dwarf star TRAPPIST-1 is home to the largest group of roughly Earth-size planets ever found in a single stellar system. Located about 40 light-years away, these seven rocky siblings provide an example of the tremendous variety of planetary systems that likely fill the universe.
A new study ...l shows that the TRAPPIST-1 planets have remarkably similar densities. That could mean they all contain about the same ratio of materials thought to compose most rocky planets, like iron, oxygen, magnesium, and silicon. But if this is the case, that ratio must be notably different than Earth’s: The TRAPPIST-1 planets are about 8% less dense than they would be if they had the same makeup as our home planet. Based on that conclusion, the paper authors hypothesized a few different mixtures of ingredients could give the TRAPPIST-1 planets the measured density. ...
Refining the transit timing and photometric analysis of TRAPPIST-1:
Masses, radii, densities, dynamics, and ephemerides ~ Eric Agol et al
- Planetary Sciences Journal 2(1):1 (Feb 2021) DOI: 10.3847/PSJ/abd022
- arXiv.org > astro-ph > arXiv:2010.01074 > 02 Oct 2020 (v1), 14 Jan 2021 ( v2)