Imaginary Picture of WASP-21 b

Display orbital revolution of WASP-21 b around the hoststar WASP-21
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Exoplanet Name : WASP-21 b
Alternate Name :
Status : Confirmed
Radius (Rjup / Re): 1.2100 (Rjup) 13.5629 (Rearth)
Mass (Mjup / Me): 0.3000 (Mjup) 95.3814 (Mearth)
Semi Major Axis / Orbital Distance Calculated 0.0520 (AU) 0.0520 (AU Est.)
Eccentricity : 0.0000
Orbital Period(Yrs) 0.0118
Orbital Period(Observed/Estimated) 4.32 (Days Obs.) 4.31 (Days Est.)
Surface Gravity (G Earth) 0.5185
Star Radiation at Atmospheric Boundary: 576662.7 (W/m2)
Measured Temperature (K) 0.0 (K)
Blackbody T 0.1(K) 1229.9 (K)
Blackbody T 0.3(K) 1155.0 (K)
Blackbody T 0.7(K) 934.5 (K)
Tidally Locked Blackbody T 0.1(K) 1462.6 (K)
Tidally Locked Blackbody T 0.3(K) 1373.6 (K)
Size Class: 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 : WASP-21
Alternate Name :
Star Distance(LY) : 750.2
Stellar Radius(Rsun) : 1.1 (Rsun Measured)
Stellar Mass(Msun) : 1.0 (Msun Measured) 1.0 (Msun Estimated)
Star Age : 0.0 (GY)
Temperature : 5800 (K)
Spectral type : G3V
UV portion[%]: 0.3
Visible portion[%]: 1.5
IR portion[%]: 98.2
Metalicity : -0.4
Absolute Magnitude: 4.8
Apparent Magnitude: 11.6
Right Ascension(RA) 347.4927
Declination (DEC) 18.3961
Hubble Space Telescope Guide Star Catalog (GSC) ID 01715-00679
Discovered by
Discovery Paper - Authors CUTRI R.M.; SKRUTSKIE M.F.; VAN DYK S.; BEICHMAN C.A.; CARPENTER J.M.; CHESTER T.; CAMBRESY L.; EVANS T.; FOWLER J.; GIZIS J.; HOWARD E.; HUCHRA J.; JARRETT T.; KOPAN E.L.; KIRKPATRICK J.D.; LIGHT R.M.; MARSH K.A.; McCALLON H.; SCHNEIDER S.; STIENING R.; SYKES M.; WEINBERG M.; WHEATON W.A.; WHEELOCK S.; ZACARIAS N.
Discovery Paper - Title 2MASS All Sky Catalog of point sources.
Discovery Paper - Journal 0
Discovery Paper - URL 0
SIMBAD LINK http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=WASP-21+&submit=SIMBAD+search
Open Exoplanet Database Link http://www.openexoplanetcatalogue.com/planet/WASP-21%20b/
WASP-21 b
WASP-21 b

  • WASP-21 b is an exoplanet orbiting the star WASP-21, located about 750.2 light-years (230.0 pc) away from Solar System. Its discovery was publicly announced on 2010.
  • The host star WASP-21 has apparent magnitude of 11.6, with absolute magnitude of 4.8.
  • It is 1.0 times more massive and 1.1 times bigger compared with our Sun. The surface temperature is 5800 with its spectral types of G3V
  • In this planetary system, the extrasolar planet WASP-21 b orbits around the star WASP-21 every 4.3 days with its orbital distance of 0.05 AU ( 7779089.3 km)
  • (Projected orbit of WASP-21 b around its host star WASP-21)


  • The Star WASP-21 's habitable zone is located at the following distance
  • Inner Boundary (the orbital distance at Venus's Equivalent Radiation ) : 0.772 AU ( 115563308.0 km)
  • Earth Boundary (the orbital distance at Earth's Equivalent Radiation) : 1.068 AU ( 159738691.9 km)
  • Outer Boundary (the orbital distance at Mars's Equivalent Radiation) : 1.627 AU ( 243406416.3 km)
  • Snow Line (the orbital distance at Snow Line Equivalent Radiation) : 2.394 AU ( 358183204.6 km)
  • Radiation at Planetary Boundary of WASP-21 b : 576662.66 W/m2

    (Habitable zone calculated based on SEAU(Solar Equivalent Astronomical Unit) around the star WASP-21)



  • Kopparapu Recent Venus for Star WASP-21 distance : 0.800 AU
  • Kopparapu Runaway Greenhouse for Earth-sized planet for Star WASP-21 distance : 1.013 AU
  • Kopparapu Runaway Greenhouse for Super-Earth-sized planet for Star WASP-21 distance : 0.978 AU
  • Kopparapu Runaway Greenhouse for Mars-sized planet for Star WASP-21 distance : 1.072 AU
  • Kopparapu Outer Boundary for Maximum Greenhouse for Star WASP-21 distance : 1.787 AU
  • Kopparapu Outer Boundary for Early Mars for Star WASP-21 distance : 1.885 AU

    (Habitable zone calculated based on Kopparapu et al.(2013) around the star WASP-21)



  • Original Kopparapu Recent Venus for Star WASP-21 distance : 0.801 AU
  • Original Kopparapu Runaway Greenhouse for Star WASP-21 distance : 1.040 AU
  • Original Kopparapu Moist Greenhouse for Star WASP-21 distance : 1.060 AU
  • Original Kopparapu Outer Boundary for Maximum Greenhouse for Star WASP-21 distance : 1.818 AU
  • Original Kopparapu Outer Boundary for Early Mars for Star WASP-21 distance : 1.891 AU

    (Habitable zone calculated based on Kopparapu et al.(Original) around the star WASP-21)



    (Position in Stellar Map of star WASP-21 and its Exoplanet WASP-21 b)



    (Zoomed position in Stellar Map of star WASP-21 and its Exoplanet WASP-21 b (zoom level 3))

    (Synthetic Spectrum of star WASP-21*)
    *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