tau Cet planetary system
tau Cet is a Sun-like main-sequence star of spectral type G8.5V approximately 11.8 light-years from Earth (3.60 parsecs). It hosts 4 confirmed exoplanets.
Host star
- Name
- tau Cet
- Spectral type
- G8.5V
- Effective temperature
- 5,310 K
- Mass
- 0.78 M☉ (solar masses)
- Radius
- 0.83 R☉ (solar radii)
- Distance
- 3.60 pc (11.8 ly)
- Hipparcos catalog
- HIP 8102
Confirmed planets (4)
| Planet | Class | Mass (M⊕) | Radius (R⊕) | Period (d) | Distance (AU) | Eq. temp (K) | Discovered |
|---|---|---|---|---|---|---|---|
| tau Cet g | Earth-sized | 1.75 | 1.18 | 20.00 | 0.1330 | — | 2017 |
| tau Cet h | Earth-sized | 1.83 | 1.19 | 49.41 | 0.2430 | — | 2017 |
| tau Cet e | Super-Earth | 3.93 | 1.81 | 162.87 | 0.5380 | — | 2017 |
| tau Cet f | Super-Earth | 3.93 | 1.81 | 636.13 | 1.3340 | — | 2017 |
The planets in detail
tau Cet g is an Earth-sized world with about 1.18 Earth radii and 1.75 Earth masses. It orbits tau Cet at 0.1330 AU with a 20.0-day year, and no published equilibrium temperature. It was confirmed in 2017 via radial velocity (Doppler) measurements.
tau Cet h is an Earth-sized world with about 1.19 Earth radii and 1.83 Earth masses. It orbits tau Cet at 0.2430 AU with a 49.4-day year, and no published equilibrium temperature. Its orbit is notably eccentric (e = 0.23), meaning the distance to its star — and the irradiation it receives — varies substantially over each year. It was confirmed in 2017 via radial velocity (Doppler) measurements.
tau Cet e is a Super-Earth with about 1.81 Earth radii and 3.93 Earth masses. It orbits tau Cet at 0.5380 AU with a 163-day year, and no published equilibrium temperature. It was confirmed in 2017 via radial velocity (Doppler) measurements.
tau Cet f is a Super-Earth with about 1.81 Earth radii and 3.93 Earth masses. It orbits tau Cet at 1.3340 AU with a 636-day year, and no published equilibrium temperature. It was confirmed in 2017 via radial velocity (Doppler) measurements.
Discovery
All 4 planets in the tau Cet system were detected in 2017 using radial velocity (Doppler) measurements. Detection facilities: Multiple Observatories.
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 26.0093°, declination -15.9338°. 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.
