HIP 81991 b
HIP 81991 b is a cold gas giant orbiting the G8 V star HIP 81991 in the constellation Hercules. It lies about 143 light-years from Earth and was discovered in 2026 using the radial velocity method.
Is HIP 81991 b in the Habitable Zone?
The position of HIP 81991 b relative to the habitable zone of HIP 81991 cannot be precisely determined from the available orbital data.
Orbit and Year Length
A year on HIP 81991 b — one full orbit around HIP 81991 — lasts 5,860.0 Earth days, longer than Jupiter's 12-year orbit. It orbits at an average distance of 6.400 AU.
How Was HIP 81991 b Discovered?
HIP 81991 b was discovered in 2026 using the radial velocity method, with observations from Multiple Facilities.
The radial velocity method measures the subtle wobble of a star caused by the gravitational pull of an orbiting planet, visible as periodic shifts in the star's light spectrum. The size of the wobble reveals the planet's minimum mass.
How Far Away Is HIP 81991 b?
HIP 81991 b is 143.2 light-years (43.9 parsecs) from Earth. Light arriving here tonight left the planet around the year 1883. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 2,520,320 years to make the journey.
The Host Star: HIP 81991
HIP 81991 b belongs to a system of 2 stars; it orbits HIP 81991.
HIP 81991
- Spectral type
- G8 V
- Surface temperature
- 5,100 K (Sun: 5,772 K)
- Mass
- 1.09 M☉
Planetary System
HIP 81991 b is the only planet known to orbit HIP 81991 so far.
HIP 81991 b — Complete Data
| Mass | 3,019.37 Earth masses (9.500 Jupiter masses) |
|---|---|
| Orbital period | 5,860.00 days |
| Orbital distance | 6.400 AU |
| Distance from Earth | 143.2 light-years (43.9 parsecs) |
| Constellation | Hercules |
| Discovery method | Radial Velocity |
| Discovery facility | Multiple Facilities |
| Discovery year | 2026 |
Data: NASA Exoplanet Archive, last updated 2026-08-20. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HIP 81991 b
Is HIP 81991 b habitable?
HIP 81991 b is not known to orbit within the habitable zone of HIP 81991, and as a cold gas giant it is an unlikely candidate for life as we know it.
How far away is HIP 81991 b?
HIP 81991 b is about 143 light-years from Earth in the constellation Hercules. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 2,520,320 years to get there.
How long is a year on HIP 81991 b?
One orbit around HIP 81991 takes 5,860.0 Earth days.
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