HD 81817 planetary system
HD 81817 is an orange main-sequence star of spectral type K3 III approximately 878 light-years from Earth (269.13 parsecs). It hosts 2 confirmed exoplanets.
Host star
- Name
- HD 81817
- Spectral type
- K3 III
- Effective temperature
- 4,140 K
- Mass
- 4.30 M☉ (solar masses)
- Radius
- 83.80 R☉ (solar radii)
- Distance
- 269.13 pc (878 ly)
- Hipparcos catalog
- HIP 47193
Confirmed planets (2)
| Planet | Class | Mass (M⊕) | Radius (R⊕) | Period (d) | Distance (AU) | Eq. temp (K) | Discovered |
|---|---|---|---|---|---|---|---|
| HD 81817 c | Neptune-like | 7185.78 | 12.00 | 622.98 | 2.3250 | — | 2022 |
| HD 81817 b | Neptune-like | 7668.56 | 12.00 | 1021.20 | 3.2330 | — | 2020 |
The planets in detail
HD 81817 c is a Neptune-like world with about 12.00 Earth radii and 7185.78 Earth masses. It orbits HD 81817 at 2.3250 AU with a 623-day year, and no published equilibrium temperature. It was confirmed in 2022 via radial velocity (Doppler) measurements.
HD 81817 b is a Neptune-like world with about 12.00 Earth radii and 7668.56 Earth masses. It orbits HD 81817 at 3.2330 AU with a 2.8-Earth-year orbit, and no published equilibrium temperature. It was confirmed in 2020 via radial velocity (Doppler) measurements.
Discovery
The HD 81817 system was first identified in 2020, with confirmation work continuing through 2022 using radial velocity (Doppler) measurements. Detection facilities: Multiple Observatories, Bohyunsan Optical Astronomical Observatory.
Observing from Earth
Exoplanets cannot be resolved visually with amateur telescopes — the host star's glare is overwhelming and even space-based direct imaging requires sophisticated coronagraphs. What you can observe is the host star itself at right ascension 144.2716°, declination 81.3263°. Use the 3D orrery above to inspect orbital geometry, planetary scale, and the habitable-zone overlay — the orbits are computed from the published Keplerian elements and animate at user-controlled time rates.
