HD 120084 b
HD 120084 b is a cold gas giant orbiting the G7 III star HD 120084 in the constellation Ursa Minor. It lies about 336 light-years from Earth and was discovered in 2013 using the radial velocity method.
Is HD 120084 b in the Habitable Zone?
HD 120084 b orbits inside the inner edge of the habitable zone of HD 120084. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 120084: 5.824–14.152 AU (conservative: 7.378–13.417 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Orbit and Year Length
A year on HD 120084 b — one full orbit around HD 120084 — lasts 2,142.0 Earth days, longer than an Earth year. It orbits at an average distance of 4.210 AU. Its orbit is highly elliptical (eccentricity 0.48), swinging dramatically closer to and farther from its star.
How Was HD 120084 b Discovered?
HD 120084 b was discovered in 2013 using the radial velocity method, with observations from Okayama Astrophysical 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 120084 b?
HD 120084 b is 336.1 light-years (103.0 parsecs) from Earth. Light arriving here tonight left the planet around the year 1690. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 5,915,360 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 120084 b scores 0.28, ranking #2,299 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 120084
HD 120084
- Spectral type
- G7 III
- Surface temperature
- 4,879 K (Sun: 5,772 K)
- Mass
- 2.16 M☉
- Radius
- 10.37 R☉
- Luminosity
- 54.6802 L☉
Planetary System
HD 120084 b is the only planet known to orbit HD 120084 so far.
HD 120084 b — Complete Data
| Mass | 2,034.10 Earth masses (6.400 Jupiter masses) |
|---|---|
| Orbital period | 2,142.00 days |
| Orbital distance | 4.210 AU |
| Eccentricity | 0.483 |
| Earth Similarity Index | 0.28 |
| Distance from Earth | 336.1 light-years (103.0 parsecs) |
| Constellation | Ursa Minor |
| Discovery method | Radial Velocity |
| Discovery facility | Okayama Astrophysical Observatory |
| Discovery year | 2013 |
Data: NASA Exoplanet Archive, last updated 2023-09-19. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 120084 b
Is HD 120084 b habitable?
No — HD 120084 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 120084 b?
HD 120084 b is about 336 light-years from Earth in the constellation Ursa Minor. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 5,915,360 years to get there.
How long is a year on HD 120084 b?
One orbit around HD 120084 takes 2,142.0 Earth days.
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