Imaginary Picture of HD 191939 b

Display orbital revolution of HD 191939 b around the hoststar HD 191939
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Exoplanet Name : HD 191939 b
Alternate Name :
Radius (Rjup / Re): 0.3024 (Rjup) 3.3896 (Rearth)
Mass (Mjup / Me): 0.0327 (Mjup) 10.3966 (Mearth)
Semi Major Axis / Orbital Distance Calculated 0.0780 (AU) 0.0780 (AU Est.)
Eccentricity : 0.0000
Orbital Period(Yrs) 0.0243
Orbital Period(Observed/Estimated) 8.88 (Days Obs.) 8.30 (Days Est.)
Surface Gravity (G Earth) 0.9049
Star Radiation at Atmospheric Boundary: 156141.6 (W/m2)
Measured Temperature (K) 0.0 (K)
Blackbody T 0.1(K) 887.2 (K)
Blackbody T 0.3(K) 833.2 (K)
Blackbody T 0.7(K) 674.1 (K)
Tidally Locked Blackbody T 0.1(K) 1055.1 (K)
Tidally Locked Blackbody T 0.3(K) 990.8 (K)
Size Class: Neptune-size
Mass Class:
Detection Type : Primary Transit
Mass Detection : Radial Velocity
Radius Detection : Primary Transit
Habitability by Solar Eq. Astronomical Unit: Not habitable
Habitability by Kopparapu: Not habitable
Star Name : HD 191939
Alternate Name :
Star Distance(LY) : 175.1
Stellar Radius(Rsun) : 0.9 (Rsun Measured)
Stellar Mass(Msun) : 0.9 (Msun Measured) 0.8 (Msun Estimated)
Star Age : 7.0 (GY)
Temperature : 5427 (K)
Spectral type : G8V
UV portion[%]: 6.5
Visible portion[%]: 42.7
IR portion[%]: 50.8
Metalicity : -0.2
Absolute Magnitude: 5.4
Apparent Magnitude: 9.0
Right Ascension(RA) 302.0240
Declination (DEC) 66.8503
Hubble Space Telescope Guide Star Catalog (GSC) ID 04244-00964
Discovered by
Discovery Paper - Authors
Discovery Paper - Title
Discovery Paper - Journal
Discovery Paper - URL
SIMBAD LINK http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+191939+&submit=SIMBAD+search
Open Exoplanet Database Link
HD 191939 b
HD 191939 b

  • HD 191939 b is an exoplanet orbiting the star HD 191939, located about 175.1 light-years (53.7 pc) away from Solar System. Its discovery was publicly announced on 2020.
  • The host star HD 191939 has apparent magnitude of 9.0, with absolute magnitude of 5.4.
  • It is 0.9 times more massive and 0.9 times bigger compared with our Sun. The surface temperature is 5427 with its spectral types of G8V
  • In this planetary system, the extrasolar planet HD 191939 b orbits around the star HD 191939 every 8.9 days with its orbital distance of 0.08 AU ( 11668633.9 km)
  • (Projected orbit of HD 191939 b around its host star HD 191939)


  • The Star HD 191939 's habitable zone is located at the following distance
  • Inner Boundary (the orbital distance at Venus's Equivalent Radiation ) : 0.603 AU ( 90200628.6 km)
  • Earth Boundary (the orbital distance at Earth's Equivalent Radiation) : 0.833 AU ( 124680841.0 km)
  • Outer Boundary (the orbital distance at Mars's Equivalent Radiation) : 1.270 AU ( 189986009.8 km)
  • Snow Line (the orbital distance at Snow Line Equivalent Radiation) : 1.869 AU ( 279572736.2 km)
  • Radiation at Planetary Boundary of HD 191939 b : 156141.56 W/m2

    (Habitable zone calculated based on SEAU(Solar Equivalent Astronomical Unit) around the star HD 191939)



  • Kopparapu Recent Venus for Star HD 191939 distance : 0.638 AU
  • Kopparapu Runaway Greenhouse for Earth-sized planet for Star HD 191939 distance : 0.808 AU
  • Kopparapu Runaway Greenhouse for Super-Earth-sized planet for Star HD 191939 distance : 0.780 AU
  • Kopparapu Runaway Greenhouse for Mars-sized planet for Star HD 191939 distance : 0.856 AU
  • Kopparapu Outer Boundary for Maximum Greenhouse for Star HD 191939 distance : 1.441 AU
  • Kopparapu Outer Boundary for Early Mars for Star HD 191939 distance : 1.520 AU

    (Habitable zone calculated based on Kopparapu et al.(2013) around the star HD 191939)



  • Original Kopparapu Recent Venus for Star HD 191939 distance : 0.635 AU
  • Original Kopparapu Runaway Greenhouse for Star HD 191939 distance : 0.831 AU
  • Original Kopparapu Moist Greenhouse for Star HD 191939 distance : 0.840 AU
  • Original Kopparapu Outer Boundary for Maximum Greenhouse for Star HD 191939 distance : 1.466 AU
  • Original Kopparapu Outer Boundary for Early Mars for Star HD 191939 distance : 1.525 AU

    (Habitable zone calculated based on Kopparapu et al.(Original) around the star HD 191939)



    (Position in Stellar Map of star HD 191939 and its Exoplanet HD 191939 b)



    (Zoomed position in Stellar Map of star HD 191939 and its Exoplanet HD 191939 b (zoom level 3))

    (Synthetic Spectrum of star HD 191939*)
    *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