HD 13931 b
HD 13931 b is a cold gas giant orbiting HD 13931 in the constellation Andromeda. It lies about 155 light-years from Earth and was discovered in 2009 using the radial velocity method.
Is HD 13931 b in the Habitable Zone?
HD 13931 b orbits beyond the outer edge of the habitable zone of HD 13931. At that distance, any surface water would almost certainly be frozen.
Habitable zone of HD 13931: 0.962–2.261 AU (conservative: 1.219–2.144 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 13931 b — one full orbit around HD 13931 — lasts 4,218.0 Earth days, longer than an Earth year. It orbits at an average distance of 5.150 AU. Its orbit is nearly circular (eccentricity 0.020).
How Was HD 13931 b Discovered?
HD 13931 b was discovered in 2009 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 13931 b?
HD 13931 b is 154.6 light-years (47.4 parsecs) from Earth. Light arriving here tonight left the planet around the year 1872. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 2,720,960 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 13931 b scores 0.13, ranking #4,304 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 13931
HD 13931
- Surface temperature
- 5,867 K (Sun: 5,772 K)
- Mass
- 1.30 M☉
- Radius
- 1.25 R☉
Planetary System
HD 13931 b is the only planet known to orbit HD 13931 so far.
HD 13931 b — Complete Data
| Mass (best estimate) | 699.23 Earth masses |
|---|---|
| Orbital period | 4,218.00 days |
| Orbital distance | 5.150 AU |
| Eccentricity | 0.020 |
| Earth Similarity Index | 0.13 |
| Distance from Earth | 154.6 light-years (47.4 parsecs) |
| Constellation | Andromeda |
| Discovery method | Radial Velocity |
| Discovery facility | W. M. Keck Observatory |
| Discovery year | 2009 |
Data: NASA Exoplanet Archive, last updated 2018-09-04. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 13931 b
Is HD 13931 b habitable?
No — HD 13931 b orbits outside the habitable zone of HD 13931 and is likely too cold for liquid water on its surface.
How far away is HD 13931 b?
HD 13931 b is about 155 light-years from Earth in the constellation Andromeda. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 2,720,960 years to get there.
How long is a year on HD 13931 b?
One orbit around HD 13931 takes 4,218.0 Earth days.
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