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an open source database of all discovered extrasolar planets


The planetary system HAT-P-8 hosts at least one planet. Note that the system is a multiple star system. It hosts at least 3 stellar components.

  System parameters
Primary system name HAT-P-8
Alternative system names N/A
Right ascension 22 52 10
Declination +35 26 50
Distance [parsec] 230±15edit
Distance [lightyears] 750±49
Number of stars in system 3
Number of planets in system 1

ArchitectureArchitecture of the system

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

  •  Stellar binary
    •  Stellar binary
      •  HAT-P-8 B, stellar object
        •  HAT-P-8 C, stellar object
        •  HAT-P-8, stellar object
          •  HAT-P-8 b, planet, semi-major axis: 0.0439 AU

        PlanetsPlanets in the system

        This table lists all planets in the system HAT-P-8.

          HAT-P-8 b
        Alternative planet names HAT-P-8 A b, 2MASS J22520985+3526495 b, TYC 2757-1152-1 b
        Description The extrasolar planet HAT-P-8b is orbiting the star HAT-P-8 in the constellation of Pegasus. It is the 11th planet discovered by the HATNet project. Variations in the optical bands may indicate the presence of strong absorbers such as TiO or VO gases. The host star is part of a hierarchical triple system.edit
        Lists Confirmed planets; Planets in binary systems, S-type
        Mass [Mjup] 1.275edit
        Mass [Mearth] 405
        Radius [Rjup] 1.321edit
        Radius [Rearth] 14.50
        Orbital period [days] 3.08edit
        Semi-major axis [AU] 0.0439edit
        Eccentricity 0.00edit
        Equilibrium temperature [K] 1713edit
        Discovery method transit
        Discovery year 2008
        Last updated [yy/mm/dd] 13/07/31

        starStars in the system

        This table lists all stars in the system HAT-P-8.

          HAT-P-8 HAT-P-8 B HAT-P-8 C
        Alternative star names HAT-P-8 A N/A N/A
        Mass [MSun] 1.192edit 0.17±0.02edit 0.131±0.011edit
        Radius [RSun] 1.475edit N/A N/A
        Age [Gyr] 4.30edit N/A N/A
        Metallicity [Fe/H] 0.0100edit N/A N/A
        Temperature [K] 6200edit 3216±59edit 3058±63edit
        Spectral type F M5V M6V
        Visual magnitude 10.36±0.03edit N/A N/A

        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).

        PlutoMercuryMarsVenusEarthNeptuneUranusSaturnJupiterHAT-P-8 b

        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.

        HAT-P-8 b

        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) 2
        Hanno Rein hanno(at) 7
        Marc-Antoine ma.martinod(at) 2
        Marc-Antoine Martinod marc-antoine.martinod(at) 6
        Ryan Varley ryanjvarley(at) 1

        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 usefule.


        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.