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The planetary system TOI-178 hosts at least 6 planets.

  System parameters
Primary system name TOI-178
Alternative system names TYC 6991-475-1
Right ascension 00 29 12.3030
Declination -30 27 13.4649
Distance [parsec] 63.0±0.2
Distance [lightyears] 205.5±0.7
Number of stars in system 1
Number of planets in system 6



This artist's impression shows the view from the planet in the TOI-178 system found orbiting furthest from the star. It is based on the known physical parameters for the planets and the star seen. Credit: ESO/L. Calcada/

ArchitectureArchitecture of the system

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

  •  TOI-178, stellar object
    •  TOI-178 b, planet, semi-major axis: 0.0261±0.0008 AU
      •  TOI-178 c, planet, semi-major axis: 0.0370±0.0011 AU
        •  TOI-178 d, planet, semi-major axis: 0.0592±0.0018 AU
          •  TOI-178 e, planet, semi-major axis: 0.078±0.002 AU
            •  TOI-178 f, planet, semi-major axis: 0.104±0.003 AU
              •  TOI-178 g, planet, semi-major axis: 0.128±0.004 AU

              PlanetsPlanets in the system

              This table lists all planets in the system TOI-178.

                TOI-178 b TOI-178 c TOI-178 d TOI-178 e TOI-178 f TOI-178 g
              Alternative planet names Gaia DR2 2318295979126499200 b, TYC 6991-475-1 b N/A N/A N/A N/A N/A
              Description The TOI-178 system is roughly 200 light-years away in the constellation of Sculptor and hosts at least six exoplanets. The five outer planets are in a complex chain of resonance, one of the longest yet discovered in a system of planets. The orbital period have the precise ratio of 18:9:6:4:3. In contrast to the well-ordered arrangement of the planets' orbits, the planets' density is much very disorderly. This contrast challenges astronomers' understanding of how planets form and evolve. The physical parameters of the system have been determined with data from the European Space Agency's CHEOPS satellite, alongside the ground-based ESPRESSO instrument on ESO's VLT and the NGTS and SPECULOOS.
              Lists Confirmed planets
              Mass [Mjup] 0.0047+0.0012−0.0014 0.0150+0.0017−0.0021 0.009+0.002−0.003 0.012±0.003 0.024±0.005 0.012+0.004−0.005
              Mass [Mearth] 1.5±0.4 4.8+0.5−0.7 3.0+0.7−0.9 3.9+1.1−1.0 7.7+1.7−1.5 3.9+1.3−1.6
              Radius [Rjup] 0.103±0.007 0.149+0.010−0.009 0.229±0.007 0.197±0.008 0.204+9.640−0.010 0.256+0.013−0.012
              Radius [Rearth] 1.15±0.07 1.67+0.11−0.10 2.57+0.07−0.08 2.21±0.09 2.29+108.05−0.11 2.87+0.14−0.13
              Orbital period [days] 1.9146±0.0000 3.2384±0.0000 6.5577±0.0000 9.9619±0.0000 15.2319±0.0001 20.7095±0.0001
              Semi-major axis [AU] 0.0261±0.0008 0.0370±0.0011 0.0592±0.0018 0.078±0.002 0.104±0.003 0.128±0.004
              Eccentricity N/A N/A N/A N/A N/A N/A
              Equilibrium temperature [K] 1040±22 873±18 690±14 600±12 521±11 470±10
              Discovery method transit
              Discovery year 2020 2018 2018 2020 2019 2020
              Last updated [yy/mm/dd] 21/01/31

              starStars in the system

              This table lists all stars in the system TOI-178.

              Alternative star names TYC 6991-475-1, Gaia DR2 2318295979126499200
              Mass [MSun] N/A
              Radius [RSun] 0.70±0.15
              Age [Gyr] N/A
              Metallicity [Fe/H] N/A
              Temperature [K] 4111±170
              Spectral type N/A
              Visual magnitude 12.00

              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).

              PlutoMercuryMarsVenusEarthNeptuneUranusSaturnJupiterTOI-178 bTOI-178 cTOI-178 dTOI-178 eTOI-178 fTOI-178 g

              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 zoneTOI-178 bTOI-178 cTOI-178 dTOI-178 eTOI-178 fTOI-178 g

              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
              Hanno Rein hanno(at) 4

              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.