HD 2039 b
HD 2039 b is a cold gas giant orbiting HD 2039 in the constellation Phoenix. It lies about 280 light-years from Earth and was discovered in 2002 using the radial velocity method.
Is HD 2039 b in the Habitable Zone?
HD 2039 b orbits beyond the outer edge of the habitable zone of HD 2039. At that distance, any surface water would almost certainly be frozen.
Habitable zone of HD 2039: 0.936–2.196 AU (conservative: 1.185–2.082 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 2039 b — one full orbit around HD 2039 — lasts 1,120.0 Earth days, longer than an Earth year. It orbits at an average distance of 2.200 AU. Its orbit is highly elliptical (eccentricity 0.71), swinging dramatically closer to and farther from its star.
How Was HD 2039 b Discovered?
HD 2039 b was discovered in 2002 using the radial velocity method, with observations from Anglo-Australian Telescope.
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 2039 b?
HD 2039 b is 279.5 light-years (85.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1747. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 4,919,200 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 2039 b scores 0.34, ranking #839 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 2039
HD 2039
- Surface temperature
- 5,945 K (Sun: 5,772 K)
- Mass
- 1.23 M☉
- Radius
- 1.19 R☉
Planetary System
HD 2039 b is the only planet known to orbit HD 2039 so far.
HD 2039 b — Complete Data
| Mass (best estimate) | 1,999.15 Earth masses |
|---|---|
| Orbital period | 1,120.00 days |
| Orbital distance | 2.200 AU |
| Eccentricity | 0.710 |
| Earth Similarity Index | 0.34 |
| Distance from Earth | 279.5 light-years (85.7 parsecs) |
| Constellation | Phoenix |
| Discovery method | Radial Velocity |
| Discovery facility | Anglo-Australian Telescope |
| Discovery year | 2002 |
Data: NASA Exoplanet Archive, last updated 2018-09-04. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 2039 b
Is HD 2039 b habitable?
No — HD 2039 b orbits outside the habitable zone of HD 2039 and is likely too cold for liquid water on its surface.
How far away is HD 2039 b?
HD 2039 b is about 280 light-years from Earth in the constellation Phoenix. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 4,919,200 years to get there.
How long is a year on HD 2039 b?
One orbit around HD 2039 takes 1,120.0 Earth days.
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