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TRAPPIST-1c

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TRAPPIST-1c
Artist's impression of TRAPPIST-1c (June 2023) with TRAPPIST-1b in the background
Discovery[1]
Discovered byMichaël Gillon et al.
Discovery siteTRAPPIST
Discovery dateMay 2, 2016
Transit
Orbital characteristics[2]
0.01580±0.00013 AU
Eccentricity0.00654±0.00188[3]
2.421937±0.000018 d
Inclination89.778°±0.118°
282.45°±17.10°[3]
StarTRAPPIST-1[4]
Physical characteristics[2]
1.097+0.014
−0.012 R🜨
Mass1.308±0.056 M🜨
Mean density
5.447+0.222
−0.235 g/cm3
1.086±0.043 g
10.65±0.42 m/s2
Temperature339.7±3.3 K (66.6 °C; 151.8 °F, equilibrium)[5]
380±31 K (107 °C; 224 °F, surface)[6]
Atmosphere
Composition by volumeNone or extremely thin[6][7][8]

TRAPPIST-1c, also designated as 2MASS J23062928-0502285 c, is a mainly rocky exoplanet orbiting around the ultracool dwarf star TRAPPIST-1, located 40.7 light-years (12.5 parsecs) away from Earth in the constellation Aquarius. It is the third most massive and third largest planet of the system, with about 131% the mass and 110% the radius of Earth.[2] Its density indicates a primarily rocky composition, and observations by the James Webb Space Telescope announced in 2023 suggests against a thick CO2 atmosphere, however this does not exclude a thick abiotic oxygen-dominated atmosphere as is hypothesized to be common around red dwarf stars.[citation needed]

Physical characteristics

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Mass, radius, and temperature

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TRAPPIST-1c was observed with the transit method, which enabled scientists to calculate its radius. Transit-timing variations and computer simulations were able to determine the mass, density, and gravity of the planet. TRAPPIST-1c is the third-largest planet of the TRAPPIST-1 system, with a radius of 1.097 R🜨. It is also the third-most massive of the system, with a mass of 1.308 M🜨, slightly lower than that of the next most massive, TRAPPIST-1g.[2] Initial estimates suggested that TRAPPIST-1c has a lower density (4.89 g/cm3) and gravity (0.966g) than Earth, consistent with a rock-based composition and a thick, Venus-like atmosphere.[3][9] However, refined density estimates show that the planet's density is similar to Earth.[2]

TRAPPIST-1c's atmosphere was expected to be large enough to raise its surface temperature far above the calculated 334.8 K (61.7 °C; 143.0 °F) equilibrium temperature.[3][9] However, an observation of the secondary eclipse of TRAPPIST-1c by the James Webb Space Telescope, announced in 2023, suggests against a thick CO2 atmosphere, however this does not exclude a thick abiotic oxygen dominated atmosphere as is hypothesized to be Common around Red dwarf stars, with a measured surface temperature of 380 K (107 °C; 224 °F).[7][6] In addition, the planet may be very geologically active due to tidal squeezing similar to Jupiter's moon Io, which happens to have a similar orbital period and eccentricity (see TRAPPIST-1#Resonance and tides for references).

Orbit

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The orbit of TRAPPIST-1c is very close to its host star. One year on the planet lasts a mere 2.42 days (58 hours), a fraction as long as that of the Solar System's innermost planet, Mercury, at 176 days. The planet orbits at a distance of 0.0158 AU, which is about 1.6% the distance between Earth and the Sun. At this proximity, TRAPPIST-1c is most likely tidally locked. However, due to the small size of its host star, the planet only receives about 2.1 times the sunlight as Earth (similar to Venus, at 1.9 times). Its orbital eccentricity is very low at 0.00654, similar to that of TRAPPIST-1b.

Host star

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TRAPPIST-1c orbits the ultracool red-dwarf star TRAPPIST-1. It is 0.121 R☉ and 0.089 M☉, with a temperature of 2511 K and an age between 3 and 8 billion years. For comparison, the Sun has a temperature of 5778 K and is about 4.5 billion years old. TRAPPIST-1 is also very dim, with about 0.0005 times (0.05%) the luminosity of the Sun. It is too faint to be seen with the naked eye, having an apparent magnitude of 18.80.

Atmosphere

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The combined transmission spectrum of TRAPPIST-1 b and c rules out a cloud-free hydrogen-dominated atmosphere for each planet, so they are unlikely to harbor an extended gas envelope. Prior to JWST observations, other atmospheres, from a cloud-free water-vapor atmosphere to a Venus-like atmosphere, remained consistent with the featureless spectrum.[10]

In 2018, the composition of TRAPPIST-1c was determined, and has been found to be rock-based. The presence of an atmosphere could not be confirmed.[11][3] An observation of the secondary eclipse of TRAPPIST-1c by the James Webb Space Telescope, announced in 2023 rules out a thick carbon dioxide atmosphere like that of Venus.[7][6] This is similar to JWST results on the inner planet TRAPPIST-1b announced earlier the same year, which suggest that it does not have a thick CO2 dominated atmosphere.[12] In 2024, transmission spectra of the planet had ruled out a hydrogen-dominated atmosphere with >3σ confidence and an atmosphere rich in water, ammonia or carbon monoxide with a pressure of 1 bar when taking into account stellar contamination.[8]

See also

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References

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  1. ^ Gillon, Michaël; Jehin, Emmanuël; Lederer, Susan M.; Delrez, Laetitia; et al. (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. ISSN 1476-4687. PMC 5321506. PMID 27135924.
  2. ^ a b c d e Agol, Eric; Dorn, Caroline; Grimm, Simon L.; Turbet, Martin; et al. (1 February 2021). "Refining the Transit-timing and Photometric Analysis of TRAPPIST-1: Masses, Radii, Densities, Dynamics, and Ephemerides". The Planetary Science Journal. 2 (1): 1. arXiv:2010.01074. Bibcode:2021PSJ.....2....1A. doi:10.3847/psj/abd022. S2CID 222125312.
  3. ^ a b c d e Grimm, Simon L.; Demory, Brice-Olivier; Gillon, Michael; Dorn, Caroline; Agol, Eric; Burdanov, Artem; Delrez, Laetitia; Sestovic, Marko; Triaud, Amaury H.M.J.; Turbet, Martin; Bolmont, Emeline; Caldas, Anthony; de Wit, Julien; Jehin, Emmanuel; Leconte, Jeremy; Raymond, Sean N.; Van Grootel, Valerie; Burgasser, Adam J.; Carey, Sean; Fabrycky, Daniel; Heng, Kevin; Hernandez, David M.; Ingalls, James G.; Lederer, Susan; Selsis, Franck; Queloz, Didier (2018). "The nature of the TRAPPIST-1 exoplanets". Astronomy & Astrophysics. 613: A68. arXiv:1802.01377. Bibcode:2018A&A...613A..68G. doi:10.1051/0004-6361/201732233. S2CID 3441829.
  4. ^ Van Grootel, Valerie; Fernandes, Catarina S.; Gillon, Michaël; Jehin, Emmanuel; Scuflaire, Richard; et al. (2018). "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.
  5. ^ Ducrot, E.; Gillon, M.; Delrez, L.; Agol, E.; et al. (1 August 2020). "TRAPPIST-1: Global results of the Spitzer Exploration Science Program Red Worlds". Astronomy & Astrophysics. 640: A112. arXiv:2006.13826. Bibcode:2020A&A...640A.112D. doi:10.1051/0004-6361/201937392. ISSN 0004-6361. S2CID 220041987.
  6. ^ a b c d Zieba, Sebastian; Kreidberg, Laura; Ducrot, Elsa; Gillon, Michaël; et al. (June 2023). "No thick carbon dioxide atmosphere on the rocky exoplanet TRAPPIST-1 c". Nature. 620 (7975): 746–749. arXiv:2306.10150. Bibcode:2023Natur.620..746Z. doi:10.1038/s41586-023-06232-z. PMC 10447244. PMID 37337068. S2CID 259200424.
  7. ^ a b c "Webb Rules Out Thick Carbon Dioxide Atmosphere for Rocky Exoplanet". webbtelescope.org. STScI. 19 June 2023. Retrieved 19 June 2023.
  8. ^ a b Radica, Michael; et al. (28 September 2024). "Promise and Peril: Stellar Contamination and Strict Limits on the Atmosphere Composition of TRAPPIST-1c from JWST NIRISS Transmission Spectra". arXiv:2409.19333v2 [astro-ph.EP].
  9. ^ a b Delrez, Laetitia; Gillon, Michael; H.M.J, Amaury; Brice-Oliver Demory, Triaud; de Wit, Julien; Ingalls, James; Agol, Eric; Bolmont, Emeline; Burdanov, Artem; Burgasser, Adam J.; Carey, Sean J.; Jehin, Emmanuel; Leconte, Jeremy; Lederer, Susan; Queloz, Didier; Selsis, Franck; Grootel, Valerie Van (2018). "Early 2017 observations of TRAPPIST-1 with Spitzer". Monthly Notices of the Royal Astronomical Society. 475 (3): 3577–3597. arXiv:1801.02554. Bibcode:2018MNRAS.475.3577D. doi:10.1093/mnras/sty051.
  10. ^ de Wit, Julien; et al. (2016). "A combined transmission spectrum of the Earth-sized exoplanets TRAPPIST-1 b and c". Nature. 537 (7618): 69–72. arXiv:1606.01103. Bibcode:2016Natur.537...69D. doi:10.1038/nature18641. PMID 27437572. S2CID 205249853.
  11. ^ Landau, NASA, Liz. "New clues to compositions of TRAPPIST-1 planets". Exoplanet Exploration: Planets Beyond our Solar System. Retrieved 21 May 2021.{{cite web}}: CS1 maint: multiple names: authors list (link)
  12. ^ "NASA's Webb Measures the Temperature of a Rocky Exoplanet". webbtelescope.org. STScI. 27 March 2023. Retrieved 27 March 2023.
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