Imaginary Picture of K2-31 Ab

Display orbital revolution of K2-31 Ab around the hoststar K2-31 A
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Exoplanet Name : K2-31 Ab
Alternate Name : "EPIC 204129699 b, 2MASS J16214578-2332520 b, EPIC 204129699.01, K2-31 A b, TYC 6794-00471-1 b, WISE J162145.75-233253.2
Status : Confirmed
Radius (Rjup / Re): 1.0600 (Rjup) 11.8815 (Rearth)
Mass (Mjup / Me): 1.7740 (Mjup) 564.0220 (Mearth)
Semi Major Axis / Orbital Distance Calculated 0.0220 (AU) 0.0220 (AU Est.)
Eccentricity : 0.0000
Orbital Period(Yrs) 0.0034
Orbital Period(Observed/Estimated) 1.26 (Days Obs.) 1.24 (Days Est.)
Surface Gravity (G Earth) 3.9953
Star Radiation at Atmospheric Boundary: 2181500.0 (W/m2)
Measured Temperature (K) 0.0 (K)
Blackbody T 0.1(K) 1715.3 (K)
Blackbody T 0.3(K) 1610.8 (K)
Blackbody T 0.7(K) 1303.3 (K)
Tidally Locked Blackbody T 0.1(K) 2039.8 (K)
Tidally Locked Blackbody T 0.3(K) 1915.6 (K)
Size Class: Jupiter-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 : K2-31 A
Alternate Name : "EPIC 204129699, TYC 6794-471-1, 2MASS 16214578-2332520"
Star Distance(LY) : 360.5
Stellar Radius(Rsun) : 1.0 (Rsun Measured)
Stellar Mass(Msun) : 0.9 (Msun Measured) 0.9 (Msun Estimated)
Star Age : 0.0 (GY)
Temperature : 5340 (K)
Spectral type : G7V
UV portion[%]: 6.0
Visible portion[%]: 41.9
IR portion[%]: 52.1
Metalicity : 0.1
Absolute Magnitude: 5.6
Apparent Magnitude: 10.8
Right Ascension(RA) 245.4408
Declination (DEC) -23.5479
Hubble Space Telescope Guide Star Catalog (GSC) ID
Discovered by
Discovery Paper - Authors
Discovery Paper - Title
Discovery Paper - Journal
Discovery Paper - URL
SIMBAD LINK
Open Exoplanet Database Link
K2-31 Ab
K2-31 Ab

  • K2-31 Ab is an exoplanet orbiting the star K2-31 A, located about 360.5 light-years (110.5 pc) away from Solar System. Its discovery was publicly announced on 2016.
  • The host star K2-31 A has apparent magnitude of 10.8, with absolute magnitude of 5.6.
  • It is 0.9 times more massive and 1.0 times bigger compared with our Sun. The surface temperature is 5340 with its spectral types of G7V
  • In this planetary system, the extrasolar planet K2-31 Ab orbits around the star K2-31 A every 1.3 days with its orbital distance of 0.02 AU ( 3291153.2 km)
  • (Projected orbit of K2-31 Ab around its host star K2-31 A)


  • The Star K2-31 A 's habitable zone is located at the following distance
  • Inner Boundary (the orbital distance at Venus's Equivalent Radiation ) : 0.636 AU ( 95094631.8 km)
  • Earth Boundary (the orbital distance at Earth's Equivalent Radiation) : 0.879 AU ( 131445632.4 km)
  • Outer Boundary (the orbital distance at Mars's Equivalent Radiation) : 1.339 AU ( 200294054.9 km)
  • Snow Line (the orbital distance at Snow Line Equivalent Radiation) : 1.970 AU ( 294741476.1 km)
  • Radiation at Planetary Boundary of K2-31 Ab : 2181500.05 W/m2

    (Habitable zone calculated based on SEAU(Solar Equivalent Astronomical Unit) around the star K2-31 A)



  • Kopparapu Recent Venus for Star K2-31 A distance : 0.676 AU
  • Kopparapu Runaway Greenhouse for Earth-sized planet for Star K2-31 A distance : 0.856 AU
  • Kopparapu Runaway Greenhouse for Super-Earth-sized planet for Star K2-31 A distance : 0.826 AU
  • Kopparapu Runaway Greenhouse for Mars-sized planet for Star K2-31 A distance : 0.907 AU
  • Kopparapu Outer Boundary for Maximum Greenhouse for Star K2-31 A distance : 1.531 AU
  • Kopparapu Outer Boundary for Early Mars for Star K2-31 A distance : 1.615 AU

    (Habitable zone calculated based on Kopparapu et al.(2013) around the star K2-31 A)



  • Original Kopparapu Recent Venus for Star K2-31 A distance : 0.671 AU
  • Original Kopparapu Runaway Greenhouse for Star K2-31 A distance : 0.881 AU
  • Original Kopparapu Moist Greenhouse for Star K2-31 A distance : 0.888 AU
  • Original Kopparapu Outer Boundary for Maximum Greenhouse for Star K2-31 A distance : 1.558 AU
  • Original Kopparapu Outer Boundary for Early Mars for Star K2-31 A distance : 1.620 AU

    (Habitable zone calculated based on Kopparapu et al.(Original) around the star K2-31 A)



    (Position in Stellar Map of star K2-31 A and its Exoplanet K2-31 Ab)



    (Zoomed position in Stellar Map of star K2-31 A and its Exoplanet K2-31 Ab (zoom level 3))

    (Synthetic Spectrum of star K2-31 A*)
    *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