HD 136418 b
HD 136418 b is a cold gas giant orbiting HD 136418 in the constellation Boötes. It lies about 343 light-years from Earth and was discovered in 2009 using the radial velocity method.
Is HD 136418 b in the Habitable Zone?
HD 136418 b orbits inside the inner edge of the habitable zone of HD 136418. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 136418: 2.209–5.342 AU (conservative: 2.797–5.065 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 136418 b — one full orbit around HD 136418 — lasts 464.3 Earth days, longer than an Earth year. It orbits at an average distance of 1.290 AU. Its orbit is mildly elliptical (eccentricity 0.25).
How Was HD 136418 b Discovered?
HD 136418 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 136418 b?
HD 136418 b is 343.0 light-years (105.2 parsecs) from Earth. Light arriving here tonight left the planet around the year 1683. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 6,036,800 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 136418 b scores 0.25, ranking #3,067 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 136418
HD 136418
- Surface temperature
- 4,989 K (Sun: 5,772 K)
- Mass
- 1.48 M☉
- Radius
- 3.78 R☉
Planetary System
HD 136418 b is the only planet known to orbit HD 136418 so far.
HD 136418 b — Complete Data
| Mass (best estimate) | 680.16 Earth masses |
|---|---|
| Orbital period | 464.30 days |
| Orbital distance | 1.290 AU |
| Eccentricity | 0.250 |
| Earth Similarity Index | 0.25 |
| Distance from Earth | 343.0 light-years (105.2 parsecs) |
| Constellation | Boötes |
| 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 136418 b
Is HD 136418 b habitable?
No — HD 136418 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 136418 b?
HD 136418 b is about 343 light-years from Earth in the constellation Boötes. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 6,036,800 years to get there.
How long is a year on HD 136418 b?
One orbit around HD 136418 takes 464.3 Earth days.
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