HD 115954 b
HD 115954 b is a cold gas giant orbiting the G0 V star HD 115954 in the constellation Canes Venatici. It lies about 286 light-years from Earth and was discovered in 2021 using the radial velocity method.
Is HD 115954 b in the Habitable Zone?
HD 115954 b orbits beyond the outer edge of the habitable zone of HD 115954. At that distance, any surface water would almost certainly be frozen.
Habitable zone of HD 115954: 0.957–2.245 AU (conservative: 1.212–2.128 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on HD 115954 b
The equilibrium temperature of HD 115954 b is about 145 K (-128 °C) — well below freezing. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C. It receives 0.06 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on HD 115954 b — one full orbit around HD 115954 — lasts 3,700.0 Earth days, longer than an Earth year. It orbits at an average distance of 5.000 AU. Its orbit is highly elliptical (eccentricity 0.49), swinging dramatically closer to and farther from its star.
How Was HD 115954 b Discovered?
HD 115954 b was discovered in 2021 using the radial velocity method, with observations from Haute-Provence 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 115954 b?
HD 115954 b is 285.9 light-years (87.6 parsecs) from Earth. Light arriving here tonight left the planet around the year 1741. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 5,031,840 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 115954 b scores 0.19, ranking #3,940 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 115954
HD 115954
- Spectral type
- G0 V
- Surface temperature
- 5,957 K (Sun: 5,772 K)
- Mass
- 1.18 M☉
- Radius
- 1.21 R☉
Planetary System
HD 115954 b is the only planet known to orbit HD 115954 so far.
HD 115954 b — Complete Data
| Mass (best estimate) | 2,634.80 Earth masses |
|---|---|
| Orbital period | 3,700.00 days |
| Orbital distance | 5.000 AU |
| Eccentricity | 0.487 |
| Equilibrium temperature | 145 K (-128 °C) |
| Stellar irradiation | 0.06× Earth |
| Earth Similarity Index | 0.19 |
| Distance from Earth | 285.9 light-years (87.6 parsecs) |
| Constellation | Canes Venatici |
| Discovery method | Radial Velocity |
| Discovery facility | Haute-Provence Observatory |
| Discovery year | 2021 |
Data: NASA Exoplanet Archive, last updated 2021-07-26. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 115954 b
Is HD 115954 b habitable?
No — HD 115954 b orbits outside the habitable zone of HD 115954 and is likely too cold for liquid water on its surface.
How far away is HD 115954 b?
HD 115954 b is about 286 light-years from Earth in the constellation Canes Venatici. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 5,031,840 years to get there.
How long is a year on HD 115954 b?
One orbit around HD 115954 takes 3,700.0 Earth days.
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