TRAPPIST-1 And Its Compact System Of Temperate Rocky Planets

By Keith Cowing
Status Report
January 24, 2024
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TRAPPIST-1 And Its Compact System Of Temperate Rocky Planets
Left : combined transit light curves of the TRAPPIST-1 planets measured by Spitzer at 4.5 µm Source: open-source (arXiv) version of Ducrot et al. (2020). Right: Transit Timing Variations (TTVs, orange/red error bars) of TRAPPIST-1 planets compared to the best-fit 8-body dynamical model (blue/green lines). Source: open-source (arXiv) version of Agol et al. (2021). — astro-ph.EP

The TRAPPIST-1 system is comprised of seven Earth-sized rocky planets in small orbits around a Jupiter-sized ultracool dwarf star 12 parsec away.

These planets cover an irradiation range similar to the range of the inner solar system. Three of them orbit within the circumstellar habitable zone. All of them are particularly well-suited for detailed characterization, thanks to the small size of and to the infrared brightness of the host star, and to the system’s compact resonant structure.

An intense transit-timing monitoring campaign resulted in unprecedented precisions on the planets’ masses and densities, and in strong constraints on their compositions. Transit transmission spectroscopy with HST discarded the presence of extended primary atmospheres around the seven planets. The first thermal emission measurements obtained with JWST favor low-density-atmosphere or bare-rock scenarios for the two inner planets.

The detection of dense secondary atmospheres around the five outer planets could be achieved by transit transmission spectroscopy with JWST, but this will require addressing the critical problem of stellar contamination with more theoretical and observational work.

Michaël Gillon

Comments: To be published in: Handbook of Exoplanets, 2nd Edition, Hans Deeg and Juan Antonio Belmonte (Eds. in Chief), Springer International Publishing AG, part of Springer Nature
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2401.11815 [astro-ph.EP] (or arXiv:2401.11815v1 [astro-ph.EP] for this version)
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Submission history
From: Michael Gillon
[v1] Mon, 22 Jan 2024 10:25:08 UTC (3,478 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻