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The planetary system TRAPPIST-1 hosts at least 7 planets.

  System parameters
Primary system name TRAPPIST-1
Alternative system names 2MASS J23062928-0502285, K2-112, EPIC 246199087
Right ascension 23 06 29.3684052886
Declination -05 02 29.031690445
Distance [parsec] 12.430±0.019
Distance [lightyears] 40.54±0.06
Number of stars in system 1
Number of planets in system 7



Artist's impression of the TRAPPIST-1 planetary system. Credit: ESO/M. Kornmesser/

ArchitectureArchitecture of the system

This list shows all planetary and stellar components in the system. It gives a quick overview of the hierarchical architecture.

  •  TRAPPIST-1, stellar object
    •  TRAPPIST-1 b, planet, semi-major axis: 0.0115±0.0000 AU
      •  TRAPPIST-1 c, planet, semi-major axis: 0.0158±0.0000 AU
        •  TRAPPIST-1 d, planet, semi-major axis: 0.0223±0.0000 AU
          •  TRAPPIST-1 e, planet, semi-major axis: 0.0293±0.0000 AU
            •  TRAPPIST-1 f, planet, semi-major axis: 0.0385±0.0000 AU
              •  TRAPPIST-1 g, planet, semi-major axis: 0.0469±0.0000 AU
                •  TRAPPIST-1 h, planet, semi-major axis: 0.0619±0.0000 AU

                PlanetsPlanets in the system

                This table lists all planets in the system TRAPPIST-1.

                Alternative planet names 2MASS J23062928-0502285 b, K2-112 b, EPIC 246199087 b, Gaia DR2 2635476908753563008 b 2MASS J23062928-0502285 c, K2-112 c, EPIC 246199087 c, Gaia DR2 2635476908753563008 c 2MASS J23062928-0502285 d, K2-112 d, EPIC 246199087 d, Gaia DR2 2635476908753563008 d 2MASS J23062928-0502285 e, K2-112 e, EPIC 246199087 e, Gaia DR2 2635476908753563008 e 2MASS J23062928-0502285 f, K2-112 f, EPIC 246199087 f, Gaia DR2 2635476908753563008 f 2MASS J23062928-0502285 g, K2-112 g, EPIC 246199087 g, Gaia DR2 2635476908753563008 g 2MASS J23062928-0502285 h, K2-112 h, EPIC 246199087 h, Gaia DR2 2635476908753563008 h
                Description Astronomers have found this system of seven Earth-sized planets just 40 light-years away. Using ground and space telescopes the planets were all detected as they passed in front of their parent star, the ultracool dwarf star known as TRAPPIST-1. The six inner planets form a near-resonant chain such that their orbital periods (1.51, 2.42, 4.04, 6.06, 9.21, 12.35 days) are near ratios of small integers. This architecture suggests that the planets formed farther from the star and migrated inward. The seven planets have equilibrium temperatures low enough to support liquid water on their surfaces.
                Lists Confirmed planets
                Mass [Mjup] 0.0032+0.0005−0.0000 0.0036±0.0004 ( 9.3+1.2−1.1 )·10-4 0.0024±0.0002 0.0029+0.0003−0.0002 0.0036±0.0003 0.0010±0.0002
                Mass [Mearth] 1.017+0.154−0.014 1.16+0.14−0.13 0.30+0.04−0.03 0.77±0.08 0.93±0.08 1.15±0.10 0.33+0.06−0.05
                Radius [Rjup] 0.100±0.003 0.098±0.003 0.070±0.002 0.081±0.002 0.093±0.003 0.102±0.003 0.069±0.002
                Radius [Rearth] 1.12±0.03 1.10±0.03 0.78±0.02 0.91±0.03 1.05±0.03 1.15±0.03 0.77±0.03
                Orbital period [days] 1.5109±0.0000 2.4218±0.0000 4.0498±0.0002 6.0996±0.0001 9.2065±0.0005 12.3528±0.0004 18.7663±0.0007
                Semi-major axis [AU] 0.0115±0.0000 0.0158±0.0000 0.0223±0.0000 0.0293±0.0000 0.0385±0.0000 0.0469±0.0000 0.0619±0.0000
                Eccentricity 0.006±0.003 0.0065±0.0019 0.0084±0.0009 0.0051±0.0006 0.0101±0.0007 0.0021±0.0006 0.0057±0.0012
                Equilibrium temperature [K] 400±8 342±7 288±6 251±5 219±4 199±4 167.0
                Discovery method transit
                Discovery year 2016 2016 2017 2017 2017 2017 2017
                Last updated [yy/mm/dd] 18/09/18

                starStars in the system

                This table lists all stars in the system TRAPPIST-1.

                Alternative star names 2MASS J23062928-0502285, K2-112, EPIC 246199087, Gaia DR2 2635476908753563008
                Mass [MSun] 0.089±0.006
                Radius [RSun] 0.121±0.003
                Age [Gyr] 8±2
                Metallicity [Fe/H] 0.04±0.08
                Temperature [K] 2516±41
                Spectral type M8 V
                Visual magnitude 18.80±0.08

                Planet sizes

                The following plot shows the approximate sizes of the planets in this system The Solar System planets are shown as a comparison. Note that unless the radius has been determined through a transit observation, this is only an approximation (see Lissauer et al. 2011b).

                PlutoMercuryMarsVenusEarthNeptuneUranusSaturnJupiterTRAPPIST-1 bTRAPPIST-1 cTRAPPIST-1 dTRAPPIST-1 eTRAPPIST-1 fTRAPPIST-1 gTRAPPIST-1 h

                Habitable zone

                The following plot shows the approximate location of the planets in this system with respect to the habitable zone (green) and the size of the star (red). This is only an estimate, using the star's spectral type and mass. Note that if no green band is shown in the plot, then the planet's orbit is far outside the habitable zone. The equations of Selsis, Kasting et al are used to draw the inner and outer boundaries.

                Habitable zoneTRAPPIST-1 bTRAPPIST-1 cTRAPPIST-1 dTRAPPIST-1 eTRAPPIST-1 fTRAPPIST-1 gTRAPPIST-1 h

                referencesScientific references and contributors

                Links to scientific papers and other data sources


                This table lists all links which are relevant to this particular system. Note that this is just a summary. More references to the scientific publications and comments can be found in the commit messages. To see these, head over the github or click here to directly go to the git blame output of this system. In the left column of the output you can see the commit message corresponding to each parameter. It also lists the date of the last commit and the person making the changes. Within the commit message, you will find a link to the scientific publication where the data is taken from. Note that this is a new feature and not all system parameters might have a reference associated with it yet. Please help making this catalogue better and contribute data or references!

                Open Exoplanet Catalogue contributors

                Contributor E-mail Number of commits
                Andrew Tribick ajtribick(at) 3
                Christian Sturm Sol-d(at) 1
                Claudionor Buzzo Raymundo raymuncb(at) 1
                Dobb13 31114721+dobb13(at) 5
                Hanno Rein hanno(at) 9

                This table lists all people who have contributed to the Open Exoplanet Catalogue. Please consider contributing! Click here to find out how. You can also view all commits contributing to this file on github.

                xmlData download

                You can download the xml file corresponding to this planetary system, which is part of the Open Exoplanet Catalogue. All information on this page has been directly generated from this XML file. You can also download the entire catalogue over at github. If you prefer to download the dataset as an ASCII tables, you might find the oec_tables repository useful.


                If you spot an error or if you can contribute additional data to this entry, please send an e-mail to Please include the corrected xml file and a reference to where the new data is coming from, ideally a scientific paper. If you are fluent with git and github, you can also create a pull request or open an issue on the Open Exoplanet Catalogue repository. Please include the reference to the relevant scientific paper in your commit message.