HD 42012 b
HD 42012 b is a cold gas giant orbiting the K0 star HD 42012 in the constellation Auriga. It lies about 120 light-years from Earth and was discovered in 2017 using the radial velocity method.
Is HD 42012 b in the Habitable Zone?
HD 42012 b orbits beyond the outer edge of the habitable zone of HD 42012. At that distance, any surface water would almost certainly be frozen.
Habitable zone of HD 42012: 0.550–1.311 AU (conservative: 0.697–1.243 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Orbit and Year Length
A year on HD 42012 b — one full orbit around HD 42012 — lasts 857.5 Earth days, longer than an Earth year. It orbits at an average distance of 1.670 AU. Its orbit is mildly elliptical (eccentricity 0.20).
How Was HD 42012 b Discovered?
HD 42012 b was discovered in 2017 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 42012 b?
HD 42012 b is 120.0 light-years (36.8 parsecs) from Earth. Light arriving here tonight left the planet around the year 1906. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 2,112,000 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 42012 b scores 0.23, ranking #3,542 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 42012
HD 42012
- Spectral type
- K0
- Surface temperature
- 5,405 K (Sun: 5,772 K)
- Mass
- 0.83 M☉
- Radius
- 0.82 R☉
- Age
- 4.1 billion years (Sun: 4.6)
Planetary System
HD 42012 b is the only planet known to orbit HD 42012 so far.
HD 42012 b — Complete Data
| Mass (best estimate) | 508.53 Earth masses |
|---|---|
| Orbital period | 857.50 days |
| Orbital distance | 1.670 AU |
| Eccentricity | 0.200 |
| Earth Similarity Index | 0.23 |
| Distance from Earth | 120.0 light-years (36.8 parsecs) |
| Constellation | Auriga |
| Discovery method | Radial Velocity |
| Discovery facility | Haute-Provence Observatory |
| Discovery year | 2017 |
Data: NASA Exoplanet Archive, last updated 2017-03-02. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 42012 b
Is HD 42012 b habitable?
No — HD 42012 b orbits outside the habitable zone of HD 42012 and is likely too cold for liquid water on its surface.
How far away is HD 42012 b?
HD 42012 b is about 120 light-years from Earth in the constellation Auriga. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 2,112,000 years to get there.
How long is a year on HD 42012 b?
One orbit around HD 42012 takes 857.5 Earth days.
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