alf Ari planetary system
alf Ari is an orange main-sequence star of spectral type K2III approximately 65.9 light-years from Earth (20.21 parsecs). It hosts 1 confirmed exoplanet.
Host star
- Name
- alf Ari
- Spectral type
- K2III
- Effective temperature
- 4,553 K
- Mass
- 1.50 M☉ (solar masses)
- Radius
- 13.90 R☉ (solar radii)
- Distance
- 20.21 pc (65.9 ly)
- Hipparcos catalog
- HIP 9884
Confirmed planets (1)
| Planet | Class | Mass (M⊕) | Radius (R⊕) | Period (d) | Distance (AU) | Eq. temp (K) | Discovered |
|---|---|---|---|---|---|---|---|
| alf Ari b | Neptune-like | 572.07 | 13.40 | 380.80 | 1.2000 | — | 2010 |
The planets in detail
alf Ari b is a Neptune-like world with about 13.40 Earth radii and 572.07 Earth masses. It orbits alf Ari at 1.2000 AU with a 381-day year, and no published equilibrium temperature. Its orbit is notably eccentric (e = 0.25), meaning the distance to its star — and the irradiation it receives — varies substantially over each year. It was confirmed in 2010 via radial velocity (Doppler) measurements.
Discovery
The single planet in the alf Ari system was confirmed in 2010 using radial velocity (Doppler) measurements. Detection facilities: 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 31.7933°, declination 23.4624°. 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.
