Imaginary Picture of HD 128311 b

Display orbital revolution of HD 128311 b around the hoststar HD 128311
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Exoplanet Name : HD 128311 b
Alternate Name :
Status : Confirmed
Radius (Rjup / Re): 0.9078 (Rjup) 10.1759 (Rearth)
Mass (Mjup / Me): 2.1800 (Mjup) 693.1048 (Mearth)
Semi Major Axis / Orbital Distance Calculated 1.0990 (AU) 1.0990 (AU Est.)
Eccentricity : 0.2500
Orbital Period(Yrs) 1.2282
Orbital Period(Observed/Estimated) 448.60 (Days Obs.) 459.14 (Days Est.)
Surface Gravity (G Earth) 6.6935
Star Radiation at Atmospheric Boundary: 328.8 (W/m2)
Measured Temperature (K) 0.0 (K)
Blackbody T 0.1(K) 190.1 (K)
Blackbody T 0.3(K) 178.5 (K)
Blackbody T 0.7(K) 144.4 (K)
Tidally Locked Blackbody T 0.1(K) 226.0 (K)
Tidally Locked Blackbody T 0.3(K) 212.2 (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 128311
Alternate Name :
Star Distance(LY) : 53.8
Stellar Radius(Rsun) : 0.7 (Rsun Measured)
Stellar Mass(Msun) : 0.8 (Msun Measured) 0.9 (Msun Estimated)
Star Age : 0.4 (GY)
Temperature : 4965 (K)
Spectral type : K0V
UV portion[%]: 3.1
Visible portion[%]: 36.7
IR portion[%]: 60.2
Metalicity : 0.1
Absolute Magnitude: 6.4
Apparent Magnitude: 7.5
Right Ascension(RA) 219.0023
Declination (DEC) 9.7464
Hubble Space Telescope Guide Star Catalog (GSC) ID 00910-00165
Discovered by
Discovery Paper - Authors Hanno Rein
Discovery Paper - Title Reanalysis of radial velocity data from the resonant planetary system HD128311
Discovery Paper - Journal Mon Not R Astron Soc Lett (2015) 448 (1): L58-L61. DOI: https://doi.org/10.1093/mnrasl/slu202
Discovery Paper - URL https://academic.oup.com/mnrasl/article/448/1/L58/2891012/Reanalysis-of-radial-velocity-data-from-the
SIMBAD LINK http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+128311+&submit=SIMBAD+search
Open Exoplanet Database Link http://www.openexoplanetcatalogue.com/planet/HD%20128311%20b/
HD 128311 b
HD 128311 b

  • HD 128311 b is an exoplanet orbiting the star HD 128311, located about 53.8 light-years (16.5 pc) away from Solar System. Its discovery was publicly announced on 2002.
  • The host star HD 128311 has apparent magnitude of 7.5, with absolute magnitude of 6.4.
  • It is 0.8 times more massive and 0.7 times bigger compared with our Sun. The surface temperature is 4965 with its spectral types of K0V
  • In this planetary system, the extrasolar planet HD 128311 b orbits around the star HD 128311 every 448.6 days with its orbital distance of 1.10 AU ( 164408059.9 km)
  • (Projected orbit of HD 128311 b around its host star HD 128311)


  • The Star HD 128311 's habitable zone is located at the following distance
  • Inner Boundary (the orbital distance at Venus's Equivalent Radiation ) : 0.390 AU ( 58320263.6 km)
  • Earth Boundary (the orbital distance at Earth's Equivalent Radiation) : 0.539 AU ( 80613845.2 km)
  • Outer Boundary (the orbital distance at Mars's Equivalent Radiation) : 0.821 AU ( 122837660.3 km)
  • Snow Line (the orbital distance at Snow Line Equivalent Radiation) : 1.208 AU ( 180760998.3 km)
  • Radiation at Planetary Boundary of HD 128311 b : 328.80 W/m2

    (Habitable zone calculated based on SEAU(Solar Equivalent Astronomical Unit) around the star HD 128311)



  • Kopparapu Recent Venus for Star HD 128311 distance : 0.422 AU
  • Kopparapu Runaway Greenhouse for Earth-sized planet for Star HD 128311 distance : 0.535 AU
  • Kopparapu Runaway Greenhouse for Super-Earth-sized planet for Star HD 128311 distance : 0.517 AU
  • Kopparapu Runaway Greenhouse for Mars-sized planet for Star HD 128311 distance : 0.567 AU
  • Kopparapu Outer Boundary for Maximum Greenhouse for Star HD 128311 distance : 0.971 AU
  • Kopparapu Outer Boundary for Early Mars for Star HD 128311 distance : 1.024 AU

    (Habitable zone calculated based on Kopparapu et al.(2013) around the star HD 128311)



  • Original Kopparapu Recent Venus for Star HD 128311 distance : 0.418 AU
  • Original Kopparapu Runaway Greenhouse for Star HD 128311 distance : 0.551 AU
  • Original Kopparapu Moist Greenhouse for Star HD 128311 distance : 0.553 AU
  • Original Kopparapu Outer Boundary for Maximum Greenhouse for Star HD 128311 distance : 0.987 AU
  • Original Kopparapu Outer Boundary for Early Mars for Star HD 128311 distance : 1.026 AU

    (Habitable zone calculated based on Kopparapu et al.(Original) around the star HD 128311)



    (Position in Stellar Map of star HD 128311 and its Exoplanet HD 128311 b)



    (Zoomed position in Stellar Map of star HD 128311 and its Exoplanet HD 128311 b (zoom level 3))

    (Synthetic Spectrum of star HD 128311*)
    *Yamashiki YA et al. 2019 ApJ 881 114
    MUSCLES Paper I - France et al. 2016 ApJ 820 89
    MUSCLES Paper II- Youngblood et al. 2016 ApJ 824 101
    MUSCLES Paper III- Loyd et al. 2016 ApJ 824 102