TRAPPIST-1e

TRAPPIST-1e, also known as 2MASS J23062928-0502285 e, is a rocky, almost earth-size exoplanet orbiting within the habitable zone around the ultracool dwarf star TRAPPIST-1 about 40 light-years (12 parsecs) away from Earth in the constellation of Aquarius. Astronomers found the exoplanet 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-1e

Artist's impression of TRAPPIST-1e from 2018, showed here as a tidally locked planet with a liquid ocean. The actual appearance of the exoplanet is right now unknown, but based on its density, it is likely not completely covered in water.
Discovery
Discovered by	Spitzer Space Telescope
Discovery date	22 February 2017
Detection method	Transit
Orbital characteristics
Apastron	0.0294322±0.000017 AU
Periastron	0.0291335±0.000017 AU
Semi-major axis	0.02928285 ± 3.4e-07[1] AU
Eccentricity	0.00510±0.00058[1]
Orbital period	6.099043 ± 0.000015[2] d
Inclination	89.860+0.10 −0.12[1]
Star	TRAPPIST-1[3]
Physical characteristics
Mean radius	0.910+0.027 −0.026[1] REarth
Mass	0.772+0.075 −0.079[1] M🜨
Mean density	5.65+0.39 −0.42 g cm−3
Surface gravity	0.930+0.063 −0.068[1] g
Temperature	Teq: 246.1 ± 3.5 K (−27.05 ± 3.50 °C; −16.69 ± 6.30 °F)[2]

The exoplanet was one of seven new exoplanets discovered orbiting the star using observations from the Spitzer Space Telescope.^[4][5] Three of the seven (e, f, and g) are in the habitable zone.^[6][7] TRAPPIST-1e is almost the same to Earth's mass, radius, density, gravity, temperature, and stellar flux.^[1][2] It is also confirmed to not have a cloud-free hydrogen-dominated atmosphere, meaning it is more likely to have a compact atmosphere like the terrestrial planets in the Solar System.^[8]

In November 2018, researchers decided that of the seven exoplanets in the multi-planetary system, TRAPPIST-1e has the best chance of being an Earth-like ocean planet, and the one most worthy of further study related to habitability.^[9] What's more, according to the Habitable Exoplanets Catalog, TRAPPIST-1e is one of the most possible habitable exoplanets discovered.^[10]

References

1. Grimm, Simon L.; Demory, Brice-Olivier; et al. (21 January 2018). "The nature of the TRAPPIST-1 exoplanets". Astronomy & Astrophysics. 613 (A68). 21. arXiv:1802.01377. Bibcode:2018A&A...613A..68G. doi:10.1051/0004-6361/201732233. S2CID 3441829. Retrieved 7 November 2022.
2. Delrez, Laetitia; Gillon, Michael; et al. (9 January 2018). "Early 2017 observations of TRAPPIST-1 with Spitzer". Monthly Notices of the Royal Astronomical Society. 475 (3): 3577. arXiv:1801.02554. Bibcode:2018MNRAS.475.3577D. doi:10.1093/mnras/sty051. S2CID 54649681. Retrieved 7 November 2022.{{cite journal}}: CS1 maint: unflagged free DOI (link)
3. van Grootel, Valerie; Fernandes, Catarina S.; et al. (5 December 2017). "Stellar parameters for TRAPPIST-1". The Astrophysical Journal. 853 (1): 30. arXiv:1712.01911. Bibcode:2018ApJ...853...30V. doi:10.3847/1538-4357/aaa023. S2CID 54034373.
4. Gillon, Michaël; Triaud, Amaury H.M.J.; et al. (23 February 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.
5. Gillon, Michaël; Jehin, Emmanuël; et al. (2 May 2016). "Temperate Earth-sized planets transiting a nearby ultracool dwarf star". Nature. 533 (7602): 221–224. arXiv:1605.07211. Bibcode:2016Natur.533..221G. doi:10.1038/nature17448. PMC 5321506. PMID 27135924.
6. NASA (February 21, 2017). "NASA telescope reveals largest batch of Earth-size, habitable-zone planets around single star". NASA.gov. Retrieved 22 February 2017.
7. NASA; Jet Propulsion Laboratory (February 22, 2017). "TRAPPIST-1 Planet Lineup". NASA's Jet Propulsion Laboratory (JPL). NASA. Retrieved 7 November 2022.
8. de Wit, Julien; Wakeford, Hannah R.; et al. (5 February 2018). "Atmospheric reconnaissance of the habitable-zone Earth-sized planets orbiting TRAPPIST-1". Nature Astronomy. 2 (3). Nature: 214–219. arXiv:1802.02250. Bibcode:2018NatAs...2..214D. doi:10.1038/s41550-017-0374-z. S2CID 119085332. Retrieved 7 November 2022.
9. Kelley, Peter (21 November 2018). "Study brings new climate models of small star TRAPPIST 1's seven intriguing worlds". EurekAlert!. University of Washington. Retrieved 22 November 2018.
10. "The Habitable Exoplanets Catalog". Planetary Habitability Laboratory @ UPR Arecibo (phl.upr.edu). University of Puerto Rico at Arecibo. December 6, 2021. Retrieved 6 February 2019.