Imaginary Picture of Kepler-257 c
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Exoplanet Name : Kepler-257 c
Alternate Name :
Radius (Rjup / Re): 0.4830 (Rjup) 5.4139 (Rearth)
Mass (Mjup / Me): 0.1105 (Mjup) 35.1166 (Mearth)
Semi Major Axis / Orbital Distance Calculated 0.0660 (AU) 0.0660 (AU Est.)
Eccentricity : 0.0000
Orbital Period(Yrs) 0.0180
Orbital Period(Observed/Estimated) 6.58 (Days Obs.) 6.02 (Days Est.)
Star Radiation at Atmospheric Boundary: 193082.3 (W/m2)
Measured Temperature (K) 0.0 (K)
Blackbody T 0.1(K) 935.6 (K)
Blackbody T 0.3(K) 878.6 (K)
Blackbody T 0.7(K) 710.9 (K)
Tidally Locked Blackbody T 0.1(K) 1112.6 (K)
Tidally Locked Blackbody T 0.3(K) 1044.8 (K)
Size Class: sub-Jupiter-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-257
Alternate Name :
Star Distance(LY) : 2507.7
Stellar Radius(Rsun) : 1.0 (Rsun Measured)
Stellar Mass(Msun) : 1.1 (Msun Measured) 0.9 (Msun Estimated)
Star Age : 0.0 (GY)
Temperature : 5188 (K)
Spectral type : K0
Metalicity : 0.3
Absolute Magnitude: 4.5
Apparent Magnitude: 13.9
Right Ascension(RA) 297.3160
Declination (DEC) 46.0233
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-257+&submit=SIMBAD+search
Open Exoplanet Database Link http://www.openexoplanetcatalogue.com/planet/Kepler-257%20c/
Kepler-257 c
Kepler-257 c

  • Kepler-257 c is an exoplanet orbiting the star Kepler-257, located about 2507.7 light-years (768.9 pc) away from Solar System. Its discovery was publicly announced on 2014.
  • The host star Kepler-257 has apparent magnitude of 13.9, with absolute magnitude of 4.5.
  • It is 1.1 times more massive and 1.0 times bigger compared with our Sun. The surface temperature is 5188 with its spectral types of K0
  • In this planetary system, the extrasolar planet Kepler-257 c orbits around the star Kepler-257 every 6.6 days with its orbital distance of 0.07 AU ( 9873459.5 km)
  • (Projected orbit of Kepler-257 c around its host star Kepler-257)


  • The Star Kepler-257 's habitable zone is located at the following distance
  • Inner Boundary (the orbital distance at Venus's Equivalent Radiation ) : 0.567 AU ( 84873260.7 km)
  • Earth Boundary (the orbital distance at Earth's Equivalent Radiation) : 0.784 AU ( 117317026.4 km)
  • Outer Boundary (the orbital distance at Mars's Equivalent Radiation) : 1.195 AU ( 178765186.0 km)
  • Snow Line (the orbital distance at Snow Line Equivalent Radiation) : 1.758 AU ( 263060802.4 km)
  • Radiation at Planetary Boundary of Kepler-257 c : 193082.31 W/m2

    (Habitable zone calculated based on SEAU(Solar Equivalent Astronomical Unit) around the star Kepler-257)



  • Kopparapu Recent Venus for Star Kepler-257 distance : 0.608 AU
  • Kopparapu Runaway Greenhouse for Earth-sized planet for Star Kepler-257 distance : 0.770 AU
  • Kopparapu Runaway Greenhouse for Super-Earth-sized planet for Star Kepler-257 distance : 0.744 AU
  • Kopparapu Runaway Greenhouse for Mars-sized planet for Star Kepler-257 distance : 0.816 AU
  • Kopparapu Outer Boundary for Maximum Greenhouse for Star Kepler-257 distance : 1.385 AU
  • Kopparapu Outer Boundary for Early Mars for Star Kepler-257 distance : 1.461 AU

    (Habitable zone calculated based on Kopparapu et al.(2013) around the star Kepler-257)



  • Original Kopparapu Recent Venus for Star Kepler-257 distance : 0.603 AU
  • Original Kopparapu Runaway Greenhouse for Star Kepler-257 distance : 0.793 AU
  • Original Kopparapu Moist Greenhouse for Star Kepler-257 distance : 0.798 AU
  • Original Kopparapu Outer Boundary for Maximum Greenhouse for Star Kepler-257 distance : 1.409 AU
  • Original Kopparapu Outer Boundary for Early Mars for Star Kepler-257 distance : 1.465 AU

    (Habitable zone calculated based on Kopparapu et al.(Original) around the star Kepler-257)



    (Position in Stellar Map of star Kepler-257 and its Exoplanet Kepler-257 c)



    (Zoomed position in Stellar Map of star Kepler-257 and its Exoplanet Kepler-257 c (zoom level 3))