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an open source database of all discovered extrasolar planets

4 UMa

The planetary system 4 UMa hosts at least one planet.

  System parameters
Primary system name 4 UMa
Alternative system names 4 Uma
Right ascension 08 40 12.81767
Declination +64 19 40.5700
Distance [parsec] 78.5edit
Distance [lightyears] 256
Number of stars in system 1
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.

  •  4 UMa, stellar object
    •  4 UMa b, planet, semi-major axis: 0.87±0.04 AU

    PlanetsPlanets in the system

    This table lists all planets in the system 4 UMa.

      4 UMa b
    Alternative planet names 4 Ursae Majoris b, pi.02 UMa b, Pi-2 Ursae Majoris b, π2 Ursae Majoris b, HD 73108 b, HIP 42527 b, TYC 4130-2355-1 b, SAO 14616 b, BD+64 698 b, HR 3404 b, 2MASS J08401279+6419405 b
    Description 4 Ursae Majoris is also known as Muscida, a name that is shared with 3 Ursae Majoris and Omicron Ursae Majoris.edit
    Lists Confirmed planets
    Mass [Mjup] 7.1±1.6edit
    Mass [Mearth] 2257±509
    Radius [Rjup] N/A
    Radius [Rearth] N/A
    Orbital period [days] 269.3±2.0edit
    Semi-major axis [AU] 0.87±0.04edit
    Eccentricity 0.43±0.02edit
    Equilibrium temperature [K] 877edit
    Discovery method RV
    Discovery year 2007
    Last updated [yy/mm/dd] 15/09/20

    starStars in the system

    This table lists all stars in the system 4 UMa.

      4 UMa
    Alternative star names 4 Ursae Majoris, pi.02 UMa, Pi-2 Ursae Majoris, π2 Ursae Majoris, HD 73108, HIP 42527, TYC 4130-2355-1, SAO 14616, BD+64 698, HR 3404, 2MASS J08401279+6419405
    Mass [MSun] 1.23±0.15edit
    Radius [RSun] 18.1±1.5edit
    Age [Gyr] 5±2edit
    Metallicity [Fe/H] -0.25±0.04edit
    Temperature [K] 4415±70edit
    Spectral type K1III
    Visual magnitude 5.787±0.005edit

    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).

    PlutoMercuryMarsVenusEarthNeptuneUranusSaturnJupiter4 UMa 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.

    4 UMa 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) 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.