Imaginary Picture of Kepler-221 d
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Exoplanet Name : Kepler-221 d
Alternate Name :
Radius (Rjup / Re): 0.2440 (Rjup) 2.7350 (Rearth)
Mass (Mjup / Me): 0.0212 (Mjup) 6.7249 (Mearth)
Semi Major Axis / Orbital Distance Calculated 0.0870 (AU) 0.0870 (AU Est.)
Eccentricity : 0.0000
Orbital Period(Yrs) 0.0275
Orbital Period(Observed/Estimated) 10.04 (Days Obs.) 11.05 (Days Est.)
Star Radiation at Atmospheric Boundary: 74300.4 (W/m2)
Measured Temperature (K) 0.0 (K)
Blackbody T 0.1(K) 736.9 (K)
Blackbody T 0.3(K) 692.0 (K)
Blackbody T 0.7(K) 559.9 (K)
Tidally Locked Blackbody T 0.1(K) 876.3 (K)
Tidally Locked Blackbody T 0.3(K) 822.9 (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 : Kepler-221
Alternate Name :
Star Distance(LY) : 1256.1
Stellar Radius(Rsun) : 0.8 (Rsun Measured)
Stellar Mass(Msun) : 0.7 (Msun Measured) 0.9 (Msun Estimated)
Star Age : 0.0 (GY)
Temperature : 5260 (K)
Spectral type : K0
Metalicity : -0.4
Absolute Magnitude: 4.5
Apparent Magnitude: 12.4
Right Ascension(RA) 296.6548
Declination (DEC) 46.8353
Hubble Space Telescope Guide Star Catalog (GSC) ID
Discovered by
Discovery Paper - Authors 0
Discovery Paper - Title
Discovery Paper - Journal 0
Discovery Paper - URL 0
SIMBAD LINK http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=Kepler-221+&submit=SIMBAD+search
Open Exoplanet Database Link http://www.openexoplanetcatalogue.com/planet/Kepler-221%20d/
Kepler-221 d
Kepler-221 d

  • Kepler-221 d is an exoplanet orbiting the star Kepler-221, located about 1256.1 light-years (385.1 pc) away from Solar System. Its discovery was publicly announced on 2014.
  • The host star Kepler-221 has apparent magnitude of 12.4, with absolute magnitude of 4.5.
  • It is 0.7 times more massive and 0.8 times bigger compared with our Sun. The surface temperature is 5260 with its spectral types of K0
  • In this planetary system, the extrasolar planet Kepler-221 d orbits around the star Kepler-221 every 10.0 days with its orbital distance of 0.09 AU ( 13015014.8 km)
  • (Projected orbit of Kepler-221 d around its host star Kepler-221)


  • The Star Kepler-221 's habitable zone is located at the following distance
  • Inner Boundary (the orbital distance at Venus's Equivalent Radiation ) : 0.464 AU ( 69401772.4 km)
  • Earth Boundary (the orbital distance at Earth's Equivalent Radiation) : 0.641 AU ( 95931386.2 km)
  • Outer Boundary (the orbital distance at Mars's Equivalent Radiation) : 0.977 AU ( 146178203.1 km)
  • Snow Line (the orbital distance at Snow Line Equivalent Radiation) : 1.438 AU ( 215107629.5 km)
  • Radiation at Planetary Boundary of Kepler-221 d : 74300.41 W/m2

    (Habitable zone calculated based on SEAU(Solar Equivalent Astronomical Unit) around the star Kepler-221)



  • Kopparapu Recent Venus for Star Kepler-221 distance : 0.495 AU
  • Kopparapu Runaway Greenhouse for Earth-sized planet for Star Kepler-221 distance : 0.627 AU
  • Kopparapu Runaway Greenhouse for Super-Earth-sized planet for Star Kepler-221 distance : 0.606 AU
  • Kopparapu Runaway Greenhouse for Mars-sized planet for Star Kepler-221 distance : 0.665 AU
  • Kopparapu Outer Boundary for Maximum Greenhouse for Star Kepler-221 distance : 1.126 AU
  • Kopparapu Outer Boundary for Early Mars for Star Kepler-221 distance : 1.187 AU

    (Habitable zone calculated based on Kopparapu et al.(2013) around the star Kepler-221)



  • Original Kopparapu Recent Venus for Star Kepler-221 distance : 0.492 AU
  • Original Kopparapu Runaway Greenhouse for Star Kepler-221 distance : 0.646 AU
  • Original Kopparapu Moist Greenhouse for Star Kepler-221 distance : 0.650 AU
  • Original Kopparapu Outer Boundary for Maximum Greenhouse for Star Kepler-221 distance : 1.145 AU
  • Original Kopparapu Outer Boundary for Early Mars for Star Kepler-221 distance : 1.190 AU

    (Habitable zone calculated based on Kopparapu et al.(Original) around the star Kepler-221)



    (Position in Stellar Map of star Kepler-221 and its Exoplanet Kepler-221 d)



    (Zoomed position in Stellar Map of star Kepler-221 and its Exoplanet Kepler-221 d (zoom level 3))