Imaginary Picture of HD 81688 b
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Exoplanet Name : HD 81688 b
Alternate Name :
Radius (Rjup / Re): 0.9078 (Rjup) 10.1759 (Rearth)
Mass (Mjup / Me): 1.7700 (Mjup) 562.7503 (Mearth)
Semi Major Axis / Orbital Distance Calculated 0.6600 (AU) 0.6600 (AU Est.)
Eccentricity : 0.0000
Orbital Period(Yrs) 0.5038
Orbital Period(Observed/Estimated) 184.02 (Days Obs.) 135.14 (Days Est.)
Star Radiation at Atmospheric Boundary: 242814.7 (W/m2)
Measured Temperature (K) 0.0 (K)
Blackbody T 0.1(K) 990.7 (K)
Blackbody T 0.3(K) 930.4 (K)
Blackbody T 0.7(K) 752.8 (K)
Tidally Locked Blackbody T 0.1(K) 1178.2 (K)
Tidally Locked Blackbody T 0.3(K) 1106.5 (K)
Size Class: Jupiter-size
Mass Class:
Detection Type : Radial Velocity
Mass Detection :
Radius Detection :
Habitability by Solar Eq. Astronomical Unit: Not habitable
Habitability by Kopparapu: Not habitable
Star Name : HD 81688
Alternate Name :
Star Distance(LY) : 280.0
Stellar Radius(Rsun) : 13.0 (Rsun Measured)
Stellar Mass(Msun) : 2.1 (Msun Measured) 1.1 (Msun Estimated)
Star Age : 0.0 (GY)
Temperature : 4753 (K)
Spectral type : K0III-IV
Metalicity : -0.4
Absolute Magnitude: 0.7
Apparent Magnitude: 5.4
Right Ascension(RA) 142.1666
Declination (DEC) 45.6014
Hubble Space Telescope Guide Star Catalog (GSC) ID
Discovered by Bunei Sato et al.
Discovery Paper - Authors "Sato,un'ei; Izumiura,ideyuki; Toyota,ri; Kambe,iji; Ikoma,asahiro; Omiya,asashi; Masuda,eiji; Takeda,oichi; Murata,aisuke; Itoh,oichi; Ando,iroyasu; Yoshida,ichitoshi; Kokubo,iichiro; Ida,higeru;"
Discovery Paper - Title "Planetary Companions around Three Intermediate-Mass G and K Giants: 18 Delphini, Aquilae, and HD 81688"
Discovery Paper - Journal 0
Discovery Paper - URL 0
SIMBAD LINK http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+81688+&submit=SIMBAD+search
Open Exoplanet Database Link http://www.openexoplanetcatalogue.com/planet/HD%2081688%20b/
HD 81688 b
HD 81688 b

  • HD 81688 b is an exoplanet orbiting the star HD 81688, located about 280.0 light-years (85.8 pc) away from Solar System. Its discovery was publicly announced on 2008.
  • The host star HD 81688 has apparent magnitude of 5.4, with absolute magnitude of 0.7.
  • It is 2.1 times more massive and 13.0 times bigger compared with our Sun. The surface temperature is 4753 with its spectral types of K0III-IV
  • In this planetary system, the extrasolar planet HD 81688 b orbits around the star HD 81688 every 184.0 days with its orbital distance of 0.66 AU ( 98734594.7 km)
  • (Projected orbit of HD 81688 b around its host star HD 81688)


  • The Star HD 81688 's habitable zone is located at the following distance
  • Inner Boundary (the orbital distance at Venus's Equivalent Radiation ) : 6.362 AU ( 951781136.9 km)
  • Earth Boundary (the orbital distance at Earth's Equivalent Radiation) : 8.794 AU ( 1315610261.3 km)
  • Outer Boundary (the orbital distance at Mars's Equivalent Radiation) : 13.401 AU ( 2004698894.3 km)
  • Snow Line (the orbital distance at Snow Line Equivalent Radiation) : 19.720 AU ( 2950002243.1 km)
  • Radiation at Planetary Boundary of HD 81688 b : 242814.66 W/m2

    (Habitable zone calculated based on SEAU(Solar Equivalent Astronomical Unit) around the star HD 81688)



  • Kopparapu Recent Venus for Star HD 81688 distance : 6.959 AU
  • Kopparapu Runaway Greenhouse for Earth-sized planet for Star HD 81688 distance : 8.810 AU
  • Kopparapu Runaway Greenhouse for Super-Earth-sized planet for Star HD 81688 distance : 8.510 AU
  • Kopparapu Runaway Greenhouse for Mars-sized planet for Star HD 81688 distance : 9.342 AU
  • Kopparapu Outer Boundary for Maximum Greenhouse for Star HD 81688 distance : 16.134 AU
  • Kopparapu Outer Boundary for Early Mars for Star HD 81688 distance : 17.019 AU

    (Habitable zone calculated based on Kopparapu et al.(2013) around the star HD 81688)



  • Original Kopparapu Recent Venus for Star HD 81688 distance : 6.873 AU
  • Original Kopparapu Runaway Greenhouse for Star HD 81688 distance : 9.087 AU
  • Original Kopparapu Moist Greenhouse for Star HD 81688 distance : 9.094 AU
  • Original Kopparapu Outer Boundary for Maximum Greenhouse for Star HD 81688 distance : 16.401 AU
  • Original Kopparapu Outer Boundary for Early Mars for Star HD 81688 distance : 17.056 AU

    (Habitable zone calculated based on Kopparapu et al.(Original) around the star HD 81688)



    (Position in Stellar Map of star HD 81688 and its Exoplanet HD 81688 b)



    (Zoomed position in Stellar Map of star HD 81688 and its Exoplanet HD 81688 b (zoom level 3))