TRAPPIST-1c

TRAPPIST-1c, also designated as 2MASS J23062928-

0502285 c, is a mainly rocky exoplanet orbiting around the TRAPPIST-1c
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
Artist's impression of TRAPPIST-1c (June
atmosphere, however this does not exclude a thick abiotic
2023) with TRAPPIST-1b in the
oxygen-dominated atmosphere as is hypothesized to be
background
common around red dwarf stars.
Discovery[1]

Physical characteristics Discovered by Michaël Gillon et al.

Discovery site TRAPPIST
Discovery date May 2, 2016
Mass, radius, and temperature
Detection Transit
TRAPPIST-1c was observed with the transit method, which method
enabled scientists to calculate its radius. Transit-timing Orbital characteristics[2]
variations and computer simulations were able to determine Semi-major 0.015 80 ± 0.000 13 AU
the mass, density, and gravity of the planet. TRAPPIST-1c is axis
the third-largest planet of the TRAPPIST-1 system, with a
Eccentricity 0.006 54 ± 0.001 88[3]
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 Orbital period 2.421 937 ± 0.000 018 d
(sidereal)
the next most massive, TRAPPIST-1g.[2] Initial estimates
suggested that TRAPPIST-1c has a lower density (4.89 Inclination 89.778° ± 0.118°
g/cm3 ) and gravity (0.966g) than Earth, consistent with a Argument of 282.45° ± 17.10°[3]
rock-based composition and a thick, Venus-like periastron
atmosphere.[3][8] However, refined density estimates show Star TRAPPIST-1[4]
that the planet's density is similar to Earth.[2]
Physical characteristics[2]
TRAPPIST-1c's atmosphere was expected to be large Mean radius +0.014
1.097 −0.012 R🜨
enough to raise its surface temperature far above the
calculated 334.8 K (61.7 °C; 143.0 °F) equilibrium Mass 1.308 ± 0.056 M🜨
temperature.[3][8] However, an observation of the secondary Mean density +0.222
5.447 −0.235 g/cm3
eclipse of TRAPPIST-1c by the James Webb Space
Surface 1.086 ± 0.043 g
Telescope, announced in 2023, suggests against a thick CO2
gravity 10.65 ± 0.42 m/s2
atmosphere, however this does not exclude a thick abiotic
oxygen dominated atmosphere as is hypothesized to be Temperature 339.7 ± 3.3 K (66.6 °C;
Common around Red dwarf stars, with a measured surface 151.8 °F, equilibrium)[5]
temperature of 380 K (107 °C; 224 °F).[7][6] In addition, the 380 ± 31 K (107 °C;
planet may be very geologically active due to tidal squeezing 224 °F, surface)[6]
similar to Jupiter's moon Io, which happens to have a similar Atmosphere
orbital period and eccentricity (see TRAPPIST-1#Resonance
Composition None or extremely
and tides for references).
by volume thin[7][6]

Orbit

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

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

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.[9]

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.[10][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.[11]

See also
55 Cancri e
GJ 1132 b

References
1. Gillon, Michaël; Jehin, Emmanuël; Lederer, Susan M.; Delrez, Laetitia; et al. (May 2016).
"Temperate Earth-sized planets transiting a nearby ultracool dwarf star" (https://www.ncbi.nl
m.nih.gov/pmc/articles/PMC5321506). Nature. 533 (7602): 221–224. arXiv:1605.07211 (http
s://arxiv.org/abs/1605.07211). Bibcode:2016Natur.533..221G (https://ui.adsabs.harvard.edu/
abs/2016Natur.533..221G). doi:10.1038/nature17448 (https://doi.org/10.1038%2Fnature174
48). ISSN 1476-4687 (https://www.worldcat.org/issn/1476-4687). PMC 5321506 (https://ww
 w.ncbi.nlm.nih.gov/pmc/articles/PMC5321506). PMID 27135924 (https://pubmed.ncbi.nlm.ni
h.gov/27135924).
2. 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 (https://arxiv.org/abs/2010.01074). Bibcode:2021PSJ.....2....1A (https://ui.a
dsabs.harvard.edu/abs/2021PSJ.....2....1A). doi:10.3847/psj/abd022 (https://doi.org/10.384
7%2Fpsj%2Fabd022). S2CID 222125312 (https://api.semanticscholar.org/CorpusID:222125
312).
3. 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 (https://arxiv.org/abs/1802.01377).
Bibcode:2018A&A...613A..68G (https://ui.adsabs.harvard.edu/abs/2018A&A...613A..68G).
doi:10.1051/0004-6361/201732233 (https://doi.org/10.1051%2F0004-6361%2F201732233).
S2CID 3441829 (https://api.semanticscholar.org/CorpusID: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 (https://arxiv.org/abs/1712.01911). Bibcode:2018ApJ...853...30V (h
ttps://ui.adsabs.harvard.edu/abs/2018ApJ...853...30V). doi:10.3847/1538-4357/aaa023 (http
s://doi.org/10.3847%2F1538-4357%2Faaa023). S2CID 54034373 (https://api.semanticschol
ar.org/CorpusID: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 (https://arxiv.org/abs/2006.13826).
Bibcode:2020A&A...640A.112D (https://ui.adsabs.harvard.edu/abs/2020A&A...640A.112D).
doi:10.1051/0004-6361/201937392 (https://doi.org/10.1051%2F0004-6361%2F201937392).
ISSN 0004-6361 (https://www.worldcat.org/issn/0004-6361). S2CID 220041987 (https://api.s
emanticscholar.org/CorpusID:220041987).
6. Zieba, Sebastian; Kreidberg, Laura; Ducrot, Elsa; Gillon, Michaël; et al. (June 2023). "No
thick carbon dioxide atmosphere on the rocky exoplanet TRAPPIST-1 c" (https://www.nature.
com/articles/s41586-023-06232-z). Nature. arXiv:2306.10150 (https://arxiv.org/abs/2306.101
50). doi:10.1038/s41586-023-06232-z (https://doi.org/10.1038%2Fs41586-023-06232-z).
7. "Webb Rules Out Thick Carbon Dioxide Atmosphere for Rocky Exoplanet" (https://webbtele
scope.org/contents/news-releases/2023/news-2023-125). webbtelescope.org. STScI. 19
June 2023. Retrieved 19 June 2023.
8. 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 (https://ar
xiv.org/abs/1801.02554). Bibcode:2018MNRAS.475.3577D (https://ui.adsabs.harvard.edu/a
bs/2018MNRAS.475.3577D). doi:10.1093/mnras/sty051 (https://doi.org/10.1093%2Fmnra
s%2Fsty051).
 9. 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 (https://arxi
v.org/abs/1606.01103). Bibcode:2016Natur.537...69D (https://ui.adsabs.harvard.edu/abs/201
6Natur.537...69D). doi:10.1038/nature18641 (https://doi.org/10.1038%2Fnature18641).
PMID 27437572 (https://pubmed.ncbi.nlm.nih.gov/27437572). S2CID 205249853 (https://ap
i.semanticscholar.org/CorpusID:205249853).
10. Landau, NASA, Liz. "New clues to compositions of TRAPPIST-1 planets" (https://exoplanet
s.nasa.gov/news/1481/new-clues-to-compositions-of-trappist-1-planets/). Exoplanet
Exploration: Planets Beyond our Solar System. Retrieved 21 May 2021.
11. "NASA's Webb Measures the Temperature of a Rocky Exoplanet" (https://webbtelescope.or
g/contents/news-releases/2023/news-2023-110). webbtelescope.org. STScI. 27 March
2023. Retrieved 27 March 2023.

Retrieved from "https://en.wikipedia.org/w/index.php?title=TRAPPIST-1c&oldid=1182572830"