HD 47186 b
HD 47186 b is a Neptune-like planet orbiting HD 47186 in the constellation Canis Major. It lies about 122 light-years from Earth and was discovered in 2008 using the radial velocity method.
Is HD 47186 b in the Habitable Zone?
HD 47186 b orbits inside the inner edge of the habitable zone of HD 47186. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 47186: 0.783–1.850 AU (conservative: 0.991–1.754 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 47186 b — one full orbit around HD 47186 — lasts 4.08 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.050 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.040).
How Was HD 47186 b Discovered?
HD 47186 b was discovered in 2008 using the radial velocity method, with observations from La Silla 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 47186 b?
HD 47186 b is 122.2 light-years (37.5 parsecs) from Earth. Light arriving here tonight left the planet around the year 1904. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 2,150,720 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 47186 b scores 0.15, ranking #4,197 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 47186
HD 47186
- Surface temperature
- 5,657 K (Sun: 5,772 K)
- Mass
- 0.96 M☉
- Radius
- 1.08 R☉
The HD 47186 Planetary System
HD 47186 b is one of 2 known planets in the HD 47186 system. Its siblings:
- HD 47186 c (Cold Gas Giant)
HD 47186 b — Complete Data
| Mass (best estimate) | 22.25 Earth masses |
|---|---|
| Orbital period | 4.08 days |
| Orbital distance | 0.050 AU |
| Eccentricity | 0.040 |
| Earth Similarity Index | 0.15 |
| Distance from Earth | 122.2 light-years (37.5 parsecs) |
| Constellation | Canis Major |
| Discovery method | Radial Velocity |
| Discovery facility | La Silla Observatory |
| Discovery year | 2008 |
Data: NASA Exoplanet Archive, last updated 2018-09-04. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 47186 b
Is HD 47186 b habitable?
No — HD 47186 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 47186 b?
HD 47186 b is about 122 light-years from Earth in the constellation Canis Major. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 2,150,720 years to get there.
How long is a year on HD 47186 b?
One orbit around HD 47186 takes 4.1 Earth days — short enough that 89 of its years would fit into one Earth year.
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