Imaginary Picture of K2-381 b

Display orbital revolution of K2-381 b around the hoststar K2-381
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Exoplanet Name : K2-381 b
Alternate Name : EPIC 217192839 b
Status : Confirmed
Radius (Rjup / Re): 0.1981 (Rjup) 2.2205 (Rearth)
Mass (Mjup / Me): 0.0174 (Mjup) 5.5400 (Mearth)
Semi Major Axis / Orbital Distance Calculated 0.1131 (AU) 0.1131 (AU Est.)
Eccentricity : 0.0000
Orbital Period(Yrs) 0.0439
Orbital Period(Observed/Estimated) 16.03 (Days Obs.) 15.99 (Days Est.)
Surface Gravity (G Earth) 1.1236
Star Radiation at Atmospheric Boundary: 17498.1 (W/m2)
Measured Temperature (K) 0.0 (K)
Blackbody T 0.1(K) 513.3 (K)
Blackbody T 0.3(K) 482.1 (K)
Blackbody T 0.7(K) 390.0 (K)
Tidally Locked Blackbody T 0.1(K) 610.4 (K)
Tidally Locked Blackbody T 0.3(K) 573.3 (K)
Size Class: sub-Neptune-size
Mass Class:
Detection Type : Primary Transit
Mass Detection :
Radius Detection : Primary Transit
Habitability by Solar Eq. Astronomical Unit: Not habitable
Habitability by Kopparapu: Not habitable
Star Name : K2-381
Alternate Name : EPIC 217192839
Star Distance(LY) : 475.2
Stellar Radius(Rsun) : 0.7 (Rsun Measured)
Stellar Mass(Msun) : 0.8 (Msun Measured) 0.7 (Msun Estimated)
Star Age : 0.0 (GY)
Temperature : 4473 (K)
Spectral type : K5
UV portion[%]: 1.5
Visible portion[%]: 30.6
IR portion[%]: 67.9
Metalicity : -0.2
Absolute Magnitude: 7.2
Apparent Magnitude: 13.0
Right Ascension(RA) 288.0250
Declination (DEC) -21.0075
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
K2-381 b
K2-381 b

  • K2-381 b is an exoplanet orbiting the star K2-381, located about 475.2 light-years (145.7 pc) away from Solar System. Its discovery was publicly announced on 2022.
  • The host star K2-381 has apparent magnitude of 13.0, with absolute magnitude of 7.2.
  • It is 0.8 times more massive and 0.7 times bigger compared with our Sun. The surface temperature is 4473 with its spectral types of K5
  • In this planetary system, the extrasolar planet K2-381 b orbits around the star K2-381 every 16.0 days with its orbital distance of 0.11 AU ( 16913535.3 km)
  • (Projected orbit of K2-381 b around its host star K2-381)


  • The Star K2-381 's habitable zone is located at the following distance
  • Inner Boundary (the orbital distance at Venus's Equivalent Radiation ) : 0.293 AU ( 43768300.3 km)
  • Earth Boundary (the orbital distance at Earth's Equivalent Radiation) : 0.404 AU ( 60499229.1 km)
  • Outer Boundary (the orbital distance at Mars's Equivalent Radiation) : 0.616 AU ( 92187436.6 km)
  • Snow Line (the orbital distance at Snow Line Equivalent Radiation) : 0.907 AU ( 135657851.5 km)
  • Radiation at Planetary Boundary of K2-381 b : 17498.06 W/m2

    (Habitable zone calculated based on SEAU(Solar Equivalent Astronomical Unit) around the star K2-381)



  • Kopparapu Recent Venus for Star K2-381 distance : 0.323 AU
  • Kopparapu Runaway Greenhouse for Earth-sized planet for Star K2-381 distance : 0.409 AU
  • Kopparapu Runaway Greenhouse for Super-Earth-sized planet for Star K2-381 distance : 0.395 AU
  • Kopparapu Runaway Greenhouse for Mars-sized planet for Star K2-381 distance : 0.434 AU
  • Kopparapu Outer Boundary for Maximum Greenhouse for Star K2-381 distance : 0.759 AU
  • Kopparapu Outer Boundary for Early Mars for Star K2-381 distance : 0.801 AU

    (Habitable zone calculated based on Kopparapu et al.(2013) around the star K2-381)



  • Original Kopparapu Recent Venus for Star K2-381 distance : 0.319 AU
  • Original Kopparapu Runaway Greenhouse for Star K2-381 distance : 0.423 AU
  • Original Kopparapu Moist Greenhouse for Star K2-381 distance : 0.422 AU
  • Original Kopparapu Outer Boundary for Maximum Greenhouse for Star K2-381 distance : 0.772 AU
  • Original Kopparapu Outer Boundary for Early Mars for Star K2-381 distance : 0.803 AU

    (Habitable zone calculated based on Kopparapu et al.(Original) around the star K2-381)



    (Position in Stellar Map of star K2-381 and its Exoplanet K2-381 b)



    (Zoomed position in Stellar Map of star K2-381 and its Exoplanet K2-381 b (zoom level 3))

    (Synthetic Spectrum of star K2-381*)
    *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