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an open source database of all discovered extrasolar planets

tau Boo

The planetary system tau Boo hosts at least one planet. Note that the system is a multiple star system. It hosts at least 2 stellar components.

  System parameters
Primary system name tau Boo
Alternative system names N/A
Right ascension 13 47 15.74340
Declination +17 27 24.8552
Distance [parsec] 15.62±0.05
Distance [lightyears] 50.95±0.16
Number of stars in system 2
Number of planets in system 1



This artist's impression shows the exoplanet Tau Bootis b. 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.

  •  Stellar binary, semi-major axis: 120±110 AU, 964±1321 years
    •  tau Boo A, stellar object
      •  tau Boo A b, planet, semi-major axis: 0.049±0.003 AU
      •  tau Boo B, stellar object

      PlanetsPlanets in the system

      This table lists all planets in the system tau Boo.

        tau Boo A b
      Alternative planet names Tau Boötis A b, Tau Bootis A b, HD 120136 A b, GJ 527 A b, Gliese 527 A b, HR 5185 b, tau Boo b
      Description The planet Tau Boötis b was one of the first exoplanets to be discovered back in 1996. In 2012, astronomers have detected the faint glow that is emitted from the planet, reliably probing the structure of the atmosphere of Tau Bootis b and deducing its mass accurately for the first time.
      Lists Confirmed planets; Planets in binary systems, S-type
      Mass [Mjup] 6.13±0.17
      Mass [Mearth] 1948±54
      Radius [Rjup] N/A
      Radius [Rearth] N/A
      Orbital period [days] 3.3125±0.0000
      Semi-major axis [AU] 0.049±0.003
      Eccentricity 0.011±0.006
      Equilibrium temperature [K] 2000
      Discovery method RV
      Discovery year 1996
      Last updated [yy/mm/dd] 14/03/04

      starStars in the system

      This table lists all stars in the system tau Boo.

        tau Boo A tau Boo B
      Alternative star names Tau Boötis A, Tau Bootis A, HD 120136 A, GJ 527 A, Gliese 527 A, HIP 67275 A, WDS J13473+1727 A, HR 5185 Tau Boötis B, Tau Bootis B, HD 120136 B, GJ 527 B, Gliese 527 B, HIP 67275 B, WDS J13473+1727 B
      Mass [MSun] 1.4±0.2 0.400
      Radius [RSun] 1.42±0.08 N/A
      Age [Gyr] 0.9±0.5 N/A
      Metallicity [Fe/H] 0.26±0.03 N/A
      Temperature [K] 6399±45 N/A
      Spectral type F7 V M2
      Visual magnitude 4.50 11.10

      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).

      PlutoMercuryMarsVenusEarthNeptuneUranusSaturnJupitertau Boo A 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.

      tau Boo A 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) 4
      Hanno Rein hanno(at) 7
      Jaroslav Merc jaroslav.merc(at) 1
      Marc-Antoine Martinod marc-antoine.martinod(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 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.