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TRAPPIST-1

Coordinates: Sky map 23h 06m 29.383s, −05° 02′ 28.59″
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TRAPPIST-1[1]

Artists' impression of TRAPPIST-1 and its seven planets
Observation data
Epoch       Equinox
Constellation Aquarius
Right ascension 23h 06m 29.283s[2]
Declination –05° 02′ 28.59″[2]
Apparent magnitude (V) 18.80
Characteristics
Spectral type M8V[3]
M8.2V[note 1]
V−R color index 2.33
R−I color index 2.47
Astrometry
Radial velocity (Rv)−56.3 km/s
Parallax (π)82.58 mas
Distance39.5 ± 1.3 ly
(12.1 ± 0.4 pc)
Absolute magnitude (MV)18.4 ± 0.1
Details
Mass0.08 ± 0.009 M☉
Mass83.8048 ± 9.428 MJup
Radius0.114 ± 0.006 R☉
Luminosity (bolometric)0.000525±0.000036[4] L☉
Luminosity (visual, LV)0.00000373[note 2] L☉
Surface gravity (log g)~5.227[note 3][5] cgs
Temperature2550 ± 55 K
Metallicity0.04 ± 0.08
Rotation1.40 ± 0.05 days
Rotational velocity (v sin i)6 ± 2 km/s
Age> 1 Gyr
Other designations
2MASS J23062928-0502285, 2MASSI J2306292-050227, 2MASSW J2306292-050227, 2MUDC 12171
Database references
SIMBADdata
Position of TRAPPIST-1 (in red) in the constellation Aquarius (the Water Carrier).

TRAPPIST-1, also known as 2MASS J23062928-0502285,[6] is an ultra-cool dwarf star[4][7] located 39 light-years (12 parsecs; 370 petametres) away from Earth in the constellation Aquarius.[8]

A team of astronomers headed by Michaël Gillon of the Institut d’Astrophysique et Géophysique [fr] at the University of Liège[9] in Belgium used the TRAPPIST (Transiting Planets and Planetesimals Small Telescope) telescope at the La Silla Observatory in the Atacama Desert, Chile,[10] to observe the star and search for orbiting planets. By utilising transit photometry, they discovered three Earth-sized planets orbiting the dwarf star; the innermost two are tidally locked to their host star while the outermost appears to lie either within the system's habitable zone or just outside of it.[7][11] The team made their observations from September to December 2015 and published its findings in the May 2016 issue of the journal Nature.[10][12]

On 22 February 2017, astronomers announced four additional exoplanets around TRAPPIST-1. This brought the total number of planets orbiting the star to seven, of which at least three, and possibly all, are in its habitable zone.[13][14]

Nomenclature

The star's name, TRAPPIST-1, reflects that it is the first star discovered by the TRAPPIST telescope to have transiting planets; the name is in honour of the Trappist Christian religious order in the Belgian region.[15]

The planets are designated in the order of their discovery, beginning with b for the first planet discovered, c for the second and so on.[16] Three planets around TRAPPIST-1 were first discovered and designated b, c and d in order of increasing orbital periods,[4] and the second batch of discoveries was similarly designated e to h.

Stellar characteristics

TRAPPIST-1 is an ultracool dwarf star that is approximately 8% the mass of and 11% the radius of the Sun. It has a temperature of 2550 K and is at least 500 million years old.[citation needed] In comparison, the Sun is about 4.6 billion years old[17] and has a temperature of 5778 K.[18]

Owing to its mass, the star has the ability to live for up to 4–5 trillion years, meaning that TRAPPIST-1 may remain a main sequence star when the Universe is much older than it is now, and when the gas needed to make stars will have been used up.[19] The star is metal-rich, with a metallicity ([Fe/H]) of 0.04, or 109% the solar amount. This is particularly odd as such low-mass stars near the boundary between brown dwarfs and hydrogen-fusing stars are expected to have considerably less metallic composition than the Sun.[citation needed] Its luminosity (L☉) is 0.04% of that of the Sun.

Planetary system

In February 2017, NASA announced in a press conference that the planetary system of this star is composed of seven Earth-like planets, three of which (e, f, g) orbit the habitable zone of its star.[20][21][22]

The TRAPPIST-1 planetary system[4][23] [24]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b 0.85±0.72 M🜨 0.01111 1.51087081 ± 0.00000060 < 0.081 89.65 ± 0.25° 1.086 ± 0.035 R🜨
c 1.38±0.61 M🜨 0.01522 2.4218233 ± 0.0000017 < 0.083 89.67 ± 0.17° 1.056 ± 0.035 R🜨
d 0.41±0.27 M🜨 0.021 ± 0.006 4.049610 ± 0.000063 < 0.070 89.75 ± 0.16° 0.772 ± 0.030 R🜨
e 0.62±0.58 M🜨 0.028 6.099615 ± 0.000011 < 0.085 89.86 ± 0.11° 0.918 ± 0.039 R🜨
f 0.68±0.18 M🜨 0.037 9.206690 ± 0.000015 < 0.063 89.680 ± 0.034° 1.045 ± 0.038 R🜨
g 1.34±0.88 M🜨 0.045 12.35294 ± 0.00012 < 0.061 89.710 ± 0.025° 1.127 ± 0.041 R🜨
h unknown M🜨 0.063+0.027
−0.013 		20+15
−6 		unknown 89.80 ± 0.07° 0.755 ± 0.034 R🜨
Artist's concept of what the TRAPPIST-1 planetary system may look like, based on available data about their diameters, masses and distances from the host star.

All seven of TRAPPIST-1's planets orbit much closer than Mercury orbits the Sun. The distance between the orbits of TRAPPIST-1b and TRAPPIST 1c is only 1.6 times the distance between the Earth and the moon. The planets should appear prominently in each others skies in some cases appearing several orders larger than the moon appears from Earth.[25][26][failed verification] A year on the closest planet passes in only 1.5 Earth days, while the sixth planet's year passes in only 12.3 days. The seventh planet's year is much less certain at 20+15
−6 days, because only a single transit has been observed. Tidally locked planets likely have very large differences in temperature between their permanently lit day sides and their permanently dark night sides, which could produce very strong winds circling the planets, while making the best places for life close to the mild twilight regions between the two sides. Another important consideration is that red dwarf stars are subject to frequent, intense flares that are likely to have stripped away the atmospheres of any planets in such close orbits.[27]

The orbits of planets b-g are nearly in resonance, having relative periods of approximately 24/24, 24/15, 24/9, 24/6, 24/4 and 24/3, respectively, or nearest-neighbor period ratios (proceeding outward) of about 8/5, 5/3, 3/2, 3/2 and 4/3 (1.603, 1.672, 1.506, 1.509 and 1.342). This represents the longest known chain of near-resonant exoplanets, and is thought to have resulted from interactions between the planets as they migrated inward within the residual protoplanetary disk after forming at greater initial distances.[4]

Strong XUV irradiation of the planetary system

An XMM-Newton X-ray study shows that the Earth-sized planets in the habitable zone of the star are subject to sufficient X-ray and EUV irradiation to significantly alter their primary and perhaps secondary atmospheres.[28]

Spectrum of TRAPPIST-1 b and c

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.[29]

  • Artist’s impression of the TRAPPIST-1 planetary system.[30]
    Artist’s impression of the TRAPPIST-1 planetary system.[30]
  • Artist's view of planets transiting red dwarf star in TRAPPIST-1 system[31]
    Artist's view of planets transiting red dwarf star in TRAPPIST-1 system[31]
  • The Sun and TRAPPIST-1 to scale. The faint star is only 11% of the diameter of the Sun and is much redder in colour.
    The Sun and TRAPPIST-1 to scale. The faint star is only 11% of the diameter of the Sun and is much redder in colour.
  • Artist's impression of a view of three planets orbiting TRAPPIST-1
    Artist's impression of a view of three planets orbiting TRAPPIST-1
  • Artist's impression of a view from TRAPPIST-1c
    Artist's impression of a view from TRAPPIST-1c
  • This artist’s impression video shows an imagined view from close to one of the three planets orbiting TRAPPIST-1
  • NASA-JPL/Caltech artist's concept of what TRAPPIST-1 planetary system may look like.
    NASA-JPL/Caltech artist's concept of what TRAPPIST-1 planetary system may look like.
  • Comparison to our solar system; all seven planets of TRAPPIST-1 could fit inside the orbit of Mercury
    Comparison to our solar system; all seven planets of TRAPPIST-1 could fit inside the orbit of Mercury

Notes

  1. ^ based on photometric spectral type estimation
  2. ^ Taking the absolute visual magnitude of TRAPPIST-1 and the absolute visual magnitude of the Sun , the visual luminosity can be calculated by
  3. ^ The surface gravity is calculated directly from Newton's law of universal gravitation, which gives the formula where M is the mass of the object, r is its radius, and G is the gravitational constant.

References

  1. ^ "TRAPPIST-1b". Open Exoplanet Catalogue. Retrieved 2 May 2016.
  2. ^ a b Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; Beichman, C. A.; Carpenter, J. M.; Chester, T.; Cambresy, L.; Evans, T.; Fowler, J.; Gizis, J.; Howard, E.; Huchra, J.; Jarrett, T.; Kopan, E. L.; Kirkpatrick, J. D.; Light, R. M.; Marsh, K. A.; McCallon, H.; Schneider, S.; Stiening, R.; Sykes, M.; Weinberg, M.; Wheaton, W. A.; Wheelock, S.; Zacarias, N. (June 2003). "2MASS All Sky Catalog of point sources". VizieR Online Data Catalog. 2246. European Southern Observatory with data provided by the SAO/NASA Astrophysics Data System. Bibcode:2003yCat.2246....0C.
  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). The American Astronomical Society: 1234. Bibcode:2006AJ....132.1234C. doi:10.1086/505706.
  4. ^ a b c d e Temperate Earth-sized planets transiting a nearby ultracool dwarf star] (pdf), European Southern Observatory
  5. ^ Viti, Serena; Jones,, Hugh R. A. (November 1999). "Gravity dependence at the bottom of the main sequence". Astronomy and Astrophysics. 351: 1028–1035. Bibcode:1999A&A...351.1028V. Retrieved 6 May 2016.{{cite journal}}: CS1 maint: extra punctuation (link)
  6. ^ "2MASS J23062928-0502285".
  7. ^ a b "Three Potentially Habitable Worlds Found Around Nearby Ultracool Dwarf Star - Currently the best place to search for life beyond the Solar System". European Southern Observatory. Retrieved 2016-05-02.
  8. ^ Chang, Kenneth (22 February 2017). "7 Earth-Size Planets Identified in Orbit Around a Dwarf Star". New York Times. Retrieved 22 February 2017.
  9. ^ "AGO - Department of Astrophysics, Geophysics and Oceanography".
  10. ^ a b "Could these newly-discovered planets orbiting an ultracool dwarf host life?". The Guardian. 2 May 2016.
  11. ^ "Three New Planets Are the Best Bets for Life". Popular Mechanics. 2016-05-02. Retrieved 2 May 2016.
  12. ^ Gillon, Michaël; Jehin, Emmanuël; Lederer, Susan M.; Delrez, Laetitia; De Wit, Julien; Burdanov, Artem; Van Grootel, Valérie; Burgasser, Adam J.; Triaud, Amaury H. M. J.; Opitom, Cyrielle; Demory, Brice-Olivier; Sahu, Devendra K.; Bardalez Gagliuffi, Daniella; Magain, Pierre; Queloz, Didier (2016). "Temperate Earth-sized planets transiting a nearby ultracool dwarf star". Nature. 533 (7602): 221–224. doi:10.1038/nature17448.
  13. ^ "Temperate Earth-Sized Planets Found in Extraordinarily Rich Planetary System TRAPPIST-1". SpaceRef. 22 February 2017. Retrieved 11 February 2017.
  14. ^ "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.
  15. ^ Gramer, Robbie (22 February 2017). "News So Foreign It's Out of This World: Scientists Discover Seven New Potentially Habitable Planets". Foreign Policy. Retrieved 23 February 2017.
  16. ^ Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
  17. ^ Fraser Cain (16 September 2008). "How Old is the Sun?". Universe Today. Retrieved 19 February 2011.
  18. ^ Fraser Cain (15 September 2008). "Temperature of the Sun". Universe Today. Retrieved 19 February 2011.
  19. ^ Adams, Fred C.; Laughlin, Gregory; Graves, Genevieve J. M. "Red Dwarfs and the End of the Main Sequence". Gravitational Collapse: From Massive Stars to Planets. Revista Mexicana de Astronomía y Astrofísica. pp. 46–49. Bibcode:2004RMxAC..22...46A. {{cite conference}}: Unknown parameter |booktitle= ignored (|book-title= suggested) (help)
  20. ^ "NASA Telescope Reveals Largest Batch of Earth-Size, Habitable-Zone Planets Around Single Star". nasa.gov. Retrieved 2017-02-22.
  21. ^ "TRAPPIST-1 Planet Lineup". jpl.nasa.gov. Retrieved 2017-02-22.
  22. ^ Wall, Mike. "Major Discovery! 7 Earth-Size Alien Planets Circle Nearby Star". space.com. Retrieved 22 February 2017.
  23. ^ 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. doi:10.1038/nature21360.
  24. ^ http://www.eso.org/public/archives/releases/sciencepapers/eso1706/eso1706a.pdf Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
  25. ^ Grush, Loren (22 February 2017). "This solar system of seven Earth-sized planets may be the best place to look for alien life".
  26. ^ "Exoplanets Exploration: Largest batch of Earth-size, habitable zone planets".
  27. ^ Airapetian, Vladimir S.; Glocer, Alex; Khazanov, George V.; Loyd, R. O. P.; France, Kevin; Sojka, Jan; Danchi, William C.; Liemohn, Michael W. (2017-01-01). "How Hospitable Are Space Weather Affected Habitable Zones? The Role of Ion Escape". The Astrophysical Journal Letters. 836 (1): L3. doi:10.3847/2041-8213/836/1/L3. ISSN 2041-8205.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  28. ^ Wheatley, Peter J.; et al. (2016). "Strong XUV irradiation of the Earth-sized exoplanets orbiting the ultracool dwarf TRAPPIST-1". Preprint. arXiv:1605.01564.
  29. ^ de Wit, Julien; et al. (2016). "A combined transmission spectrum of the Earth-sized exoplanets TRAPPIST-1 b and c". Preprint. arXiv:1606.01103.
  30. ^ "Ultracool Dwarf and the Seven Planets - Temperate Earth-sized Worlds Found in Extraordinarily Rich Planetary System". www.eso.org. Retrieved 22 February 2017.
  31. ^ "Artist's view of planets transiting red dwarf star in TRAPPIST-1 system". www.spacetelescope.org. Retrieved 21 July 2016.

Further reading

Retrieved from "https://en.wikipedia.org/w/index.php?title=TRAPPIST-1&oldid=766958301"