Imaginary Picture of HD 181720 b

Display orbital revolution of HD 181720 b around the hoststar HD 181720
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Exoplanet Name : HD 181720 b
Alternate Name :
Status : Confirmed
Radius (Rjup / Re): 0.9078 (Rjup) 10.1759 (Rearth)
Mass (Mjup / Me): 12.0000 (Mjup) 3815.2560 (Mearth)
Semi Major Axis / Orbital Distance Calculated 1.7800 (AU) 1.7800 (AU Est.)
Eccentricity : 0.2600
Orbital Period(Yrs) 2.6173
Orbital Period(Observed/Estimated) 956.00 (Days Obs.) 904.33 (Days Est.)
Surface Gravity (G Earth) 36.8452
Star Radiation at Atmospheric Boundary: 330.2 (W/m2)
Measured Temperature (K) 0.0 (K)
Blackbody T 0.1(K) 190.3 (K)
Blackbody T 0.3(K) 178.7 (K)
Blackbody T 0.7(K) 144.6 (K)
Tidally Locked Blackbody T 0.1(K) 226.3 (K)
Tidally Locked Blackbody T 0.3(K) 212.5 (K)
Size Class: Jupiter-size
Mass Class:
Detection Type : Radial Velocity
Mass Detection :
Radius Detection :
Habitability by Solar Eq. Astronomical Unit: Not habitable
Habitability by Kopparapu: Not habitable
Star Name : HD 181720
Alternate Name :
Star Distance(LY) : 189.4
Stellar Radius(Rsun) : 0.9 (Rsun Estimated)
Stellar Mass(Msun) : 0.9 (Msun Measured) 0.8 (Msun Estimated)
Star Age : 0.0 (GY)
Temperature : 5781 (K)
Spectral type : G1V
UV portion[%]: 7.8
Visible portion[%]: 44.8
IR portion[%]: 47.4
Metalicity : -0.5
Absolute Magnitude: 4.0
Apparent Magnitude: 7.9
Right Ascension(RA) 290.7208
Declination (DEC) -32.9192
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=HD+181720+&submit=SIMBAD+search
Open Exoplanet Database Link http://www.openexoplanetcatalogue.com/planet/HD%20181720%20b/
HD 181720 b
HD 181720 b

  • HD 181720 b is an exoplanet orbiting the star HD 181720, located about 189.4 light-years (58.1 pc) away from Solar System. Its discovery was publicly announced on 2009.
  • The host star HD 181720 has apparent magnitude of 7.9, with absolute magnitude of 4.0.
  • It is 0.9 times more massive and 0.9 times bigger compared with our Sun. The surface temperature is 5781 with its spectral types of G1V
  • In this planetary system, the extrasolar planet HD 181720 b orbits around the star HD 181720 every 956.0 days with its orbital distance of 1.78 AU ( 266284209.8 km)
  • (Projected orbit of HD 181720 b around its host star HD 181720)


  • The Star HD 181720 's habitable zone is located at the following distance
  • Inner Boundary (the orbital distance at Venus's Equivalent Radiation ) : 0.633 AU ( 94662632.4 km)
  • Earth Boundary (the orbital distance at Earth's Equivalent Radiation) : 0.875 AU ( 130848496.3 km)
  • Outer Boundary (the orbital distance at Mars's Equivalent Radiation) : 1.333 AU ( 199384151.6 km)
  • Snow Line (the orbital distance at Snow Line Equivalent Radiation) : 1.961 AU ( 293402513.6 km)
  • Radiation at Planetary Boundary of HD 181720 b : 330.22 W/m2

    (Habitable zone calculated based on SEAU(Solar Equivalent Astronomical Unit) around the star HD 181720)



  • Kopparapu Recent Venus for Star HD 181720 distance : 0.656 AU
  • Kopparapu Runaway Greenhouse for Earth-sized planet for Star HD 181720 distance : 0.830 AU
  • Kopparapu Runaway Greenhouse for Super-Earth-sized planet for Star HD 181720 distance : 0.802 AU
  • Kopparapu Runaway Greenhouse for Mars-sized planet for Star HD 181720 distance : 0.879 AU
  • Kopparapu Outer Boundary for Maximum Greenhouse for Star HD 181720 distance : 1.466 AU
  • Kopparapu Outer Boundary for Early Mars for Star HD 181720 distance : 1.547 AU

    (Habitable zone calculated based on Kopparapu et al.(2013) around the star HD 181720)



  • Original Kopparapu Recent Venus for Star HD 181720 distance : 0.657 AU
  • Original Kopparapu Runaway Greenhouse for Star HD 181720 distance : 0.853 AU
  • Original Kopparapu Moist Greenhouse for Star HD 181720 distance : 0.869 AU
  • Original Kopparapu Outer Boundary for Maximum Greenhouse for Star HD 181720 distance : 1.492 AU
  • Original Kopparapu Outer Boundary for Early Mars for Star HD 181720 distance : 1.552 AU

    (Habitable zone calculated based on Kopparapu et al.(Original) around the star HD 181720)



    (Position in Stellar Map of star HD 181720 and its Exoplanet HD 181720 b)



    (Zoomed position in Stellar Map of star HD 181720 and its Exoplanet HD 181720 b (zoom level 3))

    (Synthetic Spectrum of star HD 181720*)
    *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