TRAPPIST-1f, also known as 2MASS J23062928-0502285 f, is an exoplanet, potentially icy or likely rocky but under a massive water-steam gaseous envelope at very high pressure and temperature, orbiting within the habitable zone^[1] around the ultracool dwarf star TRAPPIST-1 40 light-years (12 parsecs) away from Earth in the constellation of Aquarius. The exoplanet was found by using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured.

TRAPPIST-1f

Artist's impression of TRAPPIST-1f. (February 2018)
Discovery
Discovery date	22 February 2017
Detection method	Transit
Orbital characteristics
Semi-major axis	0.037 AU (5,500,000 km)
Eccentricity	< 0.063
Orbital period	9.206690 (± 0.000015) d
Inclination	89.680 (± 0.034)
Star	TRAPPIST-1
Physical characteristics
Mean radius	1.045 (± 0.038) REarth
Mass	0.68 (± 0.18) M🜨
Surface gravity	~0.62 g
Temperature	Teq: 219 K (−54 °C; −65 °F) ≳1,400 K (1,130 °C; 2,060 °F) (surface)[2]

It was one of four new exoplanets to be discovered orbiting TRAPPIST-1 using observations from the Spitzer Space Telescope.^[3]

The planet is a eyeball planet candidate.

1. ↑ "NASA telescope reveals largest batch of Earth-size, habitable-zone planets around single star". Exoplanet Exploration: Planets Beyond our Solar System (Press release). Retrieved 22 February 2017.
2. ↑ Quarles, Billy; Quintana, Elisa V.; Lopez, Eric D.; Schlieder, Joshua E.; Barclay, Thomas (2017). "Plausible Compositions of the Seven TRAPPIST-1 Planets Using Long-term Dynamical Simulations". The Astrophysical Journal. 842 (1): L5. arXiv:1704.02261. Bibcode:2017ApJ...842L...5Q. doi:10.3847/2041-8213/aa74bf. S2CID 119474320.
3. ↑ Gillon, Michaël; Triaud, Amaury H. M. J.; Demory, Brice-Olivier; Jehin, Emmanuël; Agol, Eric; Deck, Katherine M.; Lederer, Susan M.; Wit, Julien de; Burdanov, Artem (2017). "Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1". Nature. 542 (7642): 456–460. arXiv:1703.01424. Bibcode:2017Natur.542..456G. doi:10.1038/nature21360. PMC 5330437. PMID 28230125.