HD 94771 b
HD 94771 b is a cold gas giant orbiting the G3/G5 V star HD 94771 in the constellation Hydra. It lies about 189 light-years from Earth and was discovered in 2023 using the radial velocity method.
Is HD 94771 b in the Habitable Zone?
HD 94771 b orbits beyond the outer edge of the habitable zone of HD 94771. At that distance, any surface water would almost certainly be frozen.
Habitable zone of HD 94771: 1.371–3.243 AU (conservative: 1.737–3.075 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on HD 94771 b
HD 94771 b receives 0.27 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on HD 94771 b — one full orbit around HD 94771 — lasts 2,164.0 Earth days, longer than an Earth year. It orbits at an average distance of 3.480 AU. Its orbit is highly elliptical (eccentricity 0.39), swinging dramatically closer to and farther from its star.
How Was HD 94771 b Discovered?
HD 94771 b was discovered in 2023 using the radial velocity method, with observations from La Silla Observatory.
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 HD 94771 b?
HD 94771 b is 188.5 light-years (57.8 parsecs) from Earth. Light arriving here tonight left the planet around the year 1838. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 3,317,600 years to make the journey.
Earth Similarity Index
The Earth Similarity Index (ESI) scores how physically similar a planet is to Earth, from 0 to 1, based on radius, density, escape velocity and surface temperature. HD 94771 b scores 0.27, ranking #2,427 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 94771
HD 94771
- Spectral type
- G3/G5 V
- Surface temperature
- 5,631 K (Sun: 5,772 K)
- Mass
- 1.20 M☉
- Radius
- 1.90 R☉
- Luminosity
- 3.2800 L☉
- Age
- 5.7 billion years (Sun: 4.6)
Planetary System
HD 94771 b is the only planet known to orbit HD 94771 so far.
HD 94771 b — Complete Data
| Mass (best estimate) | 169.00 Earth masses |
|---|---|
| Orbital period | 2,164.00 days |
| Orbital distance | 3.480 AU |
| Eccentricity | 0.390 |
| Stellar irradiation | 0.27× Earth |
| Earth Similarity Index | 0.27 |
| Distance from Earth | 188.5 light-years (57.8 parsecs) |
| Constellation | Hydra |
| Discovery method | Radial Velocity |
| Discovery facility | La Silla Observatory |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2023-06-27. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 94771 b
Is HD 94771 b habitable?
No — HD 94771 b orbits outside the habitable zone of HD 94771 and is likely too cold for liquid water on its surface.
How far away is HD 94771 b?
HD 94771 b is about 189 light-years from Earth in the constellation Hydra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 3,317,600 years to get there.
How long is a year on HD 94771 b?
One orbit around HD 94771 takes 2,164.0 Earth days.
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