HD 4208 b
HD 4208 b is a cold gas giant orbiting HD 4208 in the constellation Sculptor. It lies about 112 light-years from Earth and was discovered in 2001 using the radial velocity method.
Is HD 4208 b in the Habitable Zone?
HD 4208 b orbits beyond the outer edge of the habitable zone of HD 4208. At that distance, any surface water would almost certainly be frozen.
Habitable zone of HD 4208: 0.624–1.472 AU (conservative: 0.790–1.396 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 4208 b — one full orbit around HD 4208 — lasts 833.0 Earth days, longer than an Earth year. It orbits at an average distance of 1.662 AU. Its orbit is nearly circular (eccentricity 0.042).
How Was HD 4208 b Discovered?
HD 4208 b was discovered in 2001 using the radial velocity method, with observations from W. M. Keck 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 4208 b?
HD 4208 b is 111.5 light-years (34.2 parsecs) from Earth. Light arriving here tonight left the planet around the year 1915. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 1,962,400 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 4208 b scores 0.27, ranking #2,475 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 4208
HD 4208
- Surface temperature
- 5,717 K (Sun: 5,772 K)
- Mass
- 0.88 M☉
- Radius
- 0.85 R☉
- Age
- 3.8 billion years (Sun: 4.6)
Planetary System
HD 4208 b is the only planet known to orbit HD 4208 so far.
HD 4208 b — Complete Data
| Mass (best estimate) | 257.44 Earth masses |
|---|---|
| Orbital period | 832.97 days |
| Orbital distance | 1.662 AU |
| Eccentricity | 0.042 |
| Earth Similarity Index | 0.27 |
| Distance from Earth | 111.5 light-years (34.2 parsecs) |
| Constellation | Sculptor |
| Discovery method | Radial Velocity |
| Discovery facility | W. M. Keck Observatory |
| Discovery year | 2001 |
Data: NASA Exoplanet Archive, last updated 2019-06-24. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 4208 b
Is HD 4208 b habitable?
No — HD 4208 b orbits outside the habitable zone of HD 4208 and is likely too cold for liquid water on its surface.
How far away is HD 4208 b?
HD 4208 b is about 112 light-years from Earth in the constellation Sculptor. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 1,962,400 years to get there.
How long is a year on HD 4208 b?
One orbit around HD 4208 takes 833.0 Earth days.
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