Imaginary Picture of K2-38 b

Display orbital revolution of K2-38 b around the hoststar K2-38
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Exoplanet Name : K2-38 b
Alternate Name : "2MASS J16000805-2311213 b, EPIC 204221263 b, EPIC 204221263.02, TYC 6779-268-1 b, WISE J160008.01-231121.6 b"
Radius (Rjup / Re): 0.1700 (Rjup) 1.9055 (Rearth)
Mass (Mjup / Me): 0.0600 (Mjup) 19.0763 (Mearth)
Semi Major Axis / Orbital Distance Calculated 0.0499 (AU) 0.0499 (AU Est.)
Eccentricity : 0.1970
Orbital Period(Yrs) 0.0110
Orbital Period(Observed/Estimated) 4.02 (Days Obs.) 2.72 (Days Est.)
Surface Gravity (G Earth) 5.2537
Star Radiation at Atmospheric Boundary: 1028610.2 (W/m2)
Measured Temperature (K) 0.0 (K)
Blackbody T 0.1(K) 1421.4 (K)
Blackbody T 0.3(K) 1334.8 (K)
Blackbody T 0.7(K) 1080.0 (K)
Tidally Locked Blackbody T 0.1(K) 1690.3 (K)
Tidally Locked Blackbody T 0.3(K) 1587.4 (K)
Size Class: sub-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 : K2-38
Alternate Name : "2MASS J16000805-2311213, EPIC 204221263, TYC 6779-268-1, WISE J160008.01-231121.6"
Star Distance(LY) : 631.8
Stellar Radius(Rsun) : 1.4 (Rsun Measured)
Stellar Mass(Msun) : 2.2 (Msun Measured) 1.0 (Msun Estimated)
Star Age : 0.0 (GY)
Temperature : 5757 (K)
Spectral type : G2 V
UV portion[%]: 7.8
Visible portion[%]: 44.7
IR portion[%]: 47.5
Metalicity : 0.3
Absolute Magnitude: 5.0
Apparent Magnitude: 11.4
Right Ascension(RA) 240.0336
Declination (DEC) -23.1893
Hubble Space Telescope Guide Star Catalog (GSC) ID
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=K2-38+&submit=SIMBAD+search
Open Exoplanet Database Link
K2-38 b
K2-38 b

  • K2-38 b is an exoplanet orbiting the star K2-38, located about 631.8 light-years (193.7 pc) away from Solar System. Its discovery was publicly announced on 2016.
  • The host star K2-38 has apparent magnitude of 11.4, with absolute magnitude of 5.0.
  • It is 2.2 times more massive and 1.4 times bigger compared with our Sun. The surface temperature is 5757 with its spectral types of G2 V
  • In this planetary system, the extrasolar planet K2-38 b orbits around the star K2-38 every 4.0 days with its orbital distance of 0.05 AU ( 7470917.7 km)
  • (Projected orbit of K2-38 b around its host star K2-38)


  • The Star K2-38 's habitable zone is located at the following distance
  • Inner Boundary (the orbital distance at Venus's Equivalent Radiation ) : 0.991 AU ( 148227798.3 km)
  • Earth Boundary (the orbital distance at Earth's Equivalent Radiation) : 1.370 AU ( 204889553.8 km)
  • Outer Boundary (the orbital distance at Mars's Equivalent Radiation) : 2.087 AU ( 312206338.0 km)
  • Snow Line (the orbital distance at Snow Line Equivalent Radiation) : 3.071 AU ( 459425303.2 km)
  • Radiation at Planetary Boundary of K2-38 b : 1028610.20 W/m2

    (Habitable zone calculated based on SEAU(Solar Equivalent Astronomical Unit) around the star K2-38)



  • Kopparapu Recent Venus for Star K2-38 distance : 1.028 AU
  • Kopparapu Runaway Greenhouse for Earth-sized planet for Star K2-38 distance : 1.302 AU
  • Kopparapu Runaway Greenhouse for Super-Earth-sized planet for Star K2-38 distance : 1.258 AU
  • Kopparapu Runaway Greenhouse for Mars-sized planet for Star K2-38 distance : 1.379 AU
  • Kopparapu Outer Boundary for Maximum Greenhouse for Star K2-38 distance : 2.301 AU
  • Kopparapu Outer Boundary for Early Mars for Star K2-38 distance : 2.427 AU

    (Habitable zone calculated based on Kopparapu et al.(2013) around the star K2-38)



  • Original Kopparapu Recent Venus for Star K2-38 distance : 1.029 AU
  • Original Kopparapu Runaway Greenhouse for Star K2-38 distance : 1.338 AU
  • Original Kopparapu Moist Greenhouse for Star K2-38 distance : 1.362 AU
  • Original Kopparapu Outer Boundary for Maximum Greenhouse for Star K2-38 distance : 2.341 AU
  • Original Kopparapu Outer Boundary for Early Mars for Star K2-38 distance : 2.435 AU

    (Habitable zone calculated based on Kopparapu et al.(Original) around the star K2-38)



    (Position in Stellar Map of star K2-38 and its Exoplanet K2-38 b)



    (Zoomed position in Stellar Map of star K2-38 and its Exoplanet K2-38 b (zoom level 3))

    (Synthetic Spectrum of star K2-38*)
    *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