Imaginary Picture of K2-28 b

Display orbital revolution of K2-28 b around the hoststar K2-28
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Exoplanet Name : K2-28 b
Alternate Name : "EPIC 206318379, 2MASS J22222988-0757195 b, EPIC 206318379 b, EPIC 206318379.01, LP 700-6 b, WISE J222229.68-075721.8 b"
Status : Confirmed
Radius (Rjup / Re): 0.2070 (Rjup) 2.3203 (Rearth)
Mass (Mjup / Me): 0.0182 (Mjup) 5.7712 (Mearth)
Semi Major Axis / Orbital Distance Calculated 0.0214 (AU) 0.0214 (AU Est.)
Eccentricity : 0.0000
Orbital Period(Yrs) 0.0062
Orbital Period(Observed/Estimated) 2.26 (Days Obs.) 2.24 (Days Est.)
Surface Gravity (G Earth) 1.0720
Star Radiation at Atmospheric Boundary: 24030.2 (W/m2)
Measured Temperature (K) 0.0 (K)
Blackbody T 0.1(K) 555.7 (K)
Blackbody T 0.3(K) 521.9 (K)
Blackbody T 0.7(K) 422.2 (K)
Tidally Locked Blackbody T 0.1(K) 660.8 (K)
Tidally Locked Blackbody T 0.3(K) 620.6 (K)
Size Class: sub-Neptune-size
Mass Class:
Detection Type : Primary Transit
Mass Detection :
Radius Detection :
Habitability by Solar Eq. Astronomical Unit: Not habitable
Habitability by Kopparapu: Not habitable
Star Name : K2-28
Alternate Name : "EPIC 20631837, 2MASS J22222988-0757195, EPIC 206318379, LP 700-6, WISE J222229.68-075721.8"
Star Distance(LY) : 205.5
Stellar Radius(Rsun) : 0.3 (Rsun Measured)
Stellar Mass(Msun) : 0.3 (Msun Measured) 0.3 (Msun Estimated)
Star Age : 0.0 (GY)
Temperature : 3214 (K)
Spectral type : M4
UV portion[%]: 0.3
Visible portion[%]: 7.6
IR portion[%]: 92.0
Metalicity : 0.3
Absolute Magnitude: 7.7
Apparent Magnitude: 11.7
Right Ascension(RA) 335.6245
Declination (DEC) -7.9554
Hubble Space Telescope Guide Star Catalog (GSC) ID
Discovered by
Discovery Paper - Authors
Discovery Paper - Title
Discovery Paper - Journal 0
Discovery Paper - URL 0
SIMBAD LINK http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=K2-28+&submit=SIMBAD+search
Open Exoplanet Database Link
K2-28 b
K2-28 b

  • K2-28 b is an exoplanet orbiting the star K2-28, located about 205.5 light-years (63.0 pc) away from Solar System. Its discovery was publicly announced on 2016.
  • The host star K2-28 has apparent magnitude of 11.7, with absolute magnitude of 7.7.
  • It is 0.3 times more massive and 0.3 times bigger compared with our Sun. The surface temperature is 3214 with its spectral types of M4
  • In this planetary system, the extrasolar planet K2-28 b orbits around the star K2-28 every 2.3 days with its orbital distance of 0.02 AU ( 3201394.4 km)
  • (Projected orbit of K2-28 b around its host star K2-28)


  • The Star K2-28 's habitable zone is located at the following distance
  • Inner Boundary (the orbital distance at Venus's Equivalent Radiation ) : 0.065 AU ( 9708404.3 km)
  • Earth Boundary (the orbital distance at Earth's Equivalent Radiation) : 0.090 AU ( 13419551.9 km)
  • Outer Boundary (the orbital distance at Mars's Equivalent Radiation) : 0.137 AU ( 20448427.3 km)
  • Snow Line (the orbital distance at Snow Line Equivalent Radiation) : 0.201 AU ( 30090756.6 km)
  • Radiation at Planetary Boundary of K2-28 b : 24030.16 W/m2

    (Habitable zone calculated based on SEAU(Solar Equivalent Astronomical Unit) around the star K2-28)



  • Kopparapu Recent Venus for Star K2-28 distance : 0.074 AU
  • Kopparapu Runaway Greenhouse for Earth-sized planet for Star K2-28 distance : 0.093 AU
  • Kopparapu Runaway Greenhouse for Super-Earth-sized planet for Star K2-28 distance : 0.090 AU
  • Kopparapu Runaway Greenhouse for Mars-sized planet for Star K2-28 distance : 0.099 AU
  • Kopparapu Outer Boundary for Maximum Greenhouse for Star K2-28 distance : 0.184 AU
  • Kopparapu Outer Boundary for Early Mars for Star K2-28 distance : 0.194 AU

    (Habitable zone calculated based on Kopparapu et al.(2013) around the star K2-28)



  • Original Kopparapu Recent Venus for Star K2-28 distance : 0.073 AU
  • Original Kopparapu Runaway Greenhouse for Star K2-28 distance : 0.096 AU
  • Original Kopparapu Moist Greenhouse for Star K2-28 distance : 0.097 AU
  • Original Kopparapu Outer Boundary for Maximum Greenhouse for Star K2-28 distance : 0.187 AU
  • Original Kopparapu Outer Boundary for Early Mars for Star K2-28 distance : 0.194 AU

    (Habitable zone calculated based on Kopparapu et al.(Original) around the star K2-28)



    (Position in Stellar Map of star K2-28 and its Exoplanet K2-28 b)



    (Zoomed position in Stellar Map of star K2-28 and its Exoplanet K2-28 b (zoom level 3))

    (Synthetic Spectrum of star K2-28*)
    *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