TRAPPIST-1c

TRAPPIST-1c
Exoplanet List of exoplanets

Artist's impression of TRAPPIST-1c (February 2017)
Parent star
Star TRAPPIST-1[1]
Distance39.6 ± 0.4 ly
(12.1 ± 0.1 pc)
Spectral type M8V[2][3]:1236
Mass (m) 0.089 (± 0.006)[1] M☉
Radius (r) 0.121 (± 0.003)[1] R☉
Temperature (T) 2511.0 (± 37.0)[1] K
Age 3–8[2] Gyr
Orbital elements
Semi-major axis(a) 0.01581512 ± 1.5e-07[4] AU
Periastron (q) 0.015712 +0.000028
−0.00003 AU
Apastron (Q) 0.015919 +0.000028
−0.00003 AU
Eccentricity (e) 0.00654 (± 0.00108)[4]
Orbital period(P) 2.42180746 (± 0.00000091)[5] d
Inclination (i) 89.70 (± 0.18)[5]°
Physical characteristics
Mass(m)1.156 +0.131
−0.142[4] M⊕
Radius(r)1.095 +0.031
−0.030[4] R⊕
Stellar flux(F⊙)2.07 ± 0.12[5] ⊕
Density(ρ)4.87 +0.43
−0.46 g/cm3 g cm−3
Surface gravity(g)0.966 +0.087
−0.092[4] g
Temperature (T) 334.8 ± 4.7 K (61.65 ± 4.70 °C; 142.97 ± 8.46 °F) (equilibrium) (for a null albedo)[5]
Discovery information
Discovery date May 2, 2016
Discoverer(s)
Discovery method Transit
Discovery status Published

TRAPPIST-1c, also designated as 2MASS J23062928-0502285 c, is a mainly rocky, Venus-like exoplanet orbiting around the ultracool dwarf star TRAPPIST-1 approximately 40 light-years away from Earth in the constellation Aquarius. It is the most massive and third largest planet of the system, with about 116% the mass and 110% the radius of Earth. Its density indicates a primarily rocky composition with a very thick Venus-like atmosphere, although it is expected to be thinner than that of TRAPPIST-1b.

Characteristics

Mass, radius, and temperature

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 1.095 R⊕. It is also the most massive of the system as well, with a mass of 1.156 M⊕, slightly higher than that of the next most massive, TRAPPIST-1g. Despite its Earth-like mass and radius, TRAPPIST-1c has a lower density (4.89 g/cm3) and gravity (0.966g) than Earth. This is consistent with a rock-based composition and a thick, Venus-like atmosphere of water vapor, similar to TRAPPIST-1b. TRAPPIST-1c's atmosphere is expected to be thinner than that of its inner sibling, but still large enough to raise its surface temperature far above the calculated 334.8 K (61.7 °C; 143.0 °F) equilibrium temperature.[4][5]

Orbit

The orbit of TRAPPIST-1c is very close to its host star. One year on this planet lasts a mere 2.42 days (58 hours), a fraction as long as that of our Solar System's innermost planet, Mercury. 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. Its orbital eccentricity is very low at 0.00654, similar to that of TRAPPIST-1b.

Host star

TRAPPIST-1c orbits the ultracool 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 see 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. Other atmospheres, from a cloud-free water-vapor atmosphere to a Venus-like atmosphere, remain consistent with the featureless spectrum.[6]

In 2018, the composition of TRAPPIST-1c was determined, with turned out to be rock-based with a very thick, Venus-like atmosphere. The atmosphere of TRAPPIST-1c is likely thinner than that of TRAPPIST-1b.[7][4]

See also

References

  1. 1 2 3 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: 30. arXiv:1712.01911. doi:10.3847/1538-4357/aaa023.
  2. 1 2 "Planet TRAPPIST-1 c". Exoplanet.eu. Retrieved 2016-05-06.
  3. ↑ Costa, E.; Mendez, R. A.; Jao, W.-C.; Henry, T. J.; Subasavage, J. P.; Ianna, P. A. (August 4, 2006). "The Solar Neighborhood. XVI. Parallaxes from CTIOPI: Final Results from the 1.5 m Telescope Program" (PDF). The Astronomical Journal. 132 (3): 1234. Bibcode:2006AJ....132.1234C. CiteSeerX 10.1.1.622.2310. doi:10.1086/505706.
  4. 1 2 3 4 5 6 7 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. doi:10.1051/0004-6361/201732233.
  5. 1 2 3 4 5 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. doi:10.1093/mnras/sty051.
  6. ↑ 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.
  7. ↑ https://exoplanets.nasa.gov/news/1481/new-clues-to-compositions-of-trappist-1-planets/
  8. Gillon, Michaël; Triaud, Amaury H. M. J.; et al. (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.
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