Imaginary Picture of K2-261 b

Display orbital revolution of K2-261 b around the hoststar K2-261
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Exoplanet Name : K2-261 b
Alternate Name : "EPIC 201498078 b, 2MASS J10520778+0029359 b, TYC 255-257-1 b, WISE J105207.76+002935.6 b"
Status : Confirmed
Radius (Rjup / Re): 0.8500 (Rjup) 9.5276 (Rearth)
Mass (Mjup / Me): 0.2230 (Mjup) 70.9002 (Mearth)
Semi Major Axis / Orbital Distance Calculated 0.1020 (AU) 0.1020 (AU Est.)
Eccentricity : 0.3900
Orbital Period(Yrs) 0.0318
Orbital Period(Observed/Estimated) 11.63 (Days Obs.) 11.34 (Days Est.)
Surface Gravity (G Earth) 0.7810
Star Radiation at Atmospheric Boundary: 301627.2 (W/m2)
Measured Temperature (K) 0.0 (K)
Blackbody T 0.1(K) 1045.9 (K)
Blackbody T 0.3(K) 982.3 (K)
Blackbody T 0.7(K) 794.7 (K)
Tidally Locked Blackbody T 0.1(K) 1243.8 (K)
Tidally Locked Blackbody T 0.3(K) 1168.1 (K)
Size Class: Jupiter-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 : K2-261
Alternate Name : "EPIC 201498078, 2MASS J10520778+0029359, TYC 255-257-1, WISE J105207.76+002935.6"
Star Distance(LY) : 701.1
Stellar Radius(Rsun) : 1.6 (Rsun Measured)
Stellar Mass(Msun) : 1.1 (Msun Measured) 1.0 (Msun Estimated)
Star Age : 8.8 (GY)
Temperature : 5537 (K)
Spectral type : G7 IV/V
UV portion[%]: 7.0
Visible portion[%]: 43.5
IR portion[%]: 49.5
Metalicity : 0.4
Absolute Magnitude: 3.9
Apparent Magnitude: 10.6
Right Ascension(RA) 163.0324
Declination (DEC) 0.4934
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=K2-261+&submit=SIMBAD+search
Open Exoplanet Database Link
K2-261 b
K2-261 b

  • K2-261 b is an exoplanet orbiting the star K2-261, located about 701.1 light-years (214.9 pc) away from Solar System. Its discovery was publicly announced on 2018.
  • The host star K2-261 has apparent magnitude of 10.6, with absolute magnitude of 3.9.
  • It is 1.1 times more massive and 1.6 times bigger compared with our Sun. The surface temperature is 5537 with its spectral types of G7 IV/V
  • In this planetary system, the extrasolar planet K2-261 b orbits around the star K2-261 every 11.6 days with its orbital distance of 0.10 AU ( 15258982.8 km)
  • (Projected orbit of K2-261 b around its host star K2-261)


  • The Star K2-261 's habitable zone is located at the following distance
  • Inner Boundary (the orbital distance at Venus's Equivalent Radiation ) : 1.096 AU ( 163942330.2 km)
  • Earth Boundary (the orbital distance at Earth's Equivalent Radiation) : 1.515 AU ( 226611143.6 km)
  • Outer Boundary (the orbital distance at Mars's Equivalent Radiation) : 2.308 AU ( 345305233.9 km)
  • Snow Line (the orbital distance at Snow Line Equivalent Radiation) : 3.397 AU ( 508131778.6 km)
  • Radiation at Planetary Boundary of K2-261 b : 301627.16 W/m2

    (Habitable zone calculated based on SEAU(Solar Equivalent Astronomical Unit) around the star K2-261)



  • Kopparapu Recent Venus for Star K2-261 distance : 1.152 AU
  • Kopparapu Runaway Greenhouse for Earth-sized planet for Star K2-261 distance : 1.459 AU
  • Kopparapu Runaway Greenhouse for Super-Earth-sized planet for Star K2-261 distance : 1.409 AU
  • Kopparapu Runaway Greenhouse for Mars-sized planet for Star K2-261 distance : 1.545 AU
  • Kopparapu Outer Boundary for Maximum Greenhouse for Star K2-261 distance : 2.594 AU
  • Kopparapu Outer Boundary for Early Mars for Star K2-261 distance : 2.736 AU

    (Habitable zone calculated based on Kopparapu et al.(2013) around the star K2-261)



  • Original Kopparapu Recent Venus for Star K2-261 distance : 1.148 AU
  • Original Kopparapu Runaway Greenhouse for Star K2-261 distance : 1.500 AU
  • Original Kopparapu Moist Greenhouse for Star K2-261 distance : 1.520 AU
  • Original Kopparapu Outer Boundary for Maximum Greenhouse for Star K2-261 distance : 2.639 AU
  • Original Kopparapu Outer Boundary for Early Mars for Star K2-261 distance : 2.745 AU

    (Habitable zone calculated based on Kopparapu et al.(Original) around the star K2-261)



    (Position in Stellar Map of star K2-261 and its Exoplanet K2-261 b)



    (Zoomed position in Stellar Map of star K2-261 and its Exoplanet K2-261 b (zoom level 3))

    (Synthetic Spectrum of star K2-261*)
    *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