HD 11755 b
HD 11755 b is a cold gas giant orbiting HD 11755 in the constellation Cassiopeia. It lies about 767 light-years from Earth and was discovered in 2015 using the radial velocity method.
Is HD 11755 b in the Habitable Zone?
HD 11755 b orbits inside the inner edge of the habitable zone of HD 11755. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 11755: 9.222–22.987 AU (conservative: 11.681–21.793 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 11755 b — one full orbit around HD 11755 — lasts 433.7 Earth days, longer than an Earth year. It orbits at an average distance of 1.090 AU — comparable to the inner Solar System. Its orbit is mildly elliptical (eccentricity 0.19).
How Was HD 11755 b Discovered?
HD 11755 b was discovered in 2015 using the radial velocity method, with observations from Bohyunsan Optical Astronomical 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 11755 b?
HD 11755 b is 766.6 light-years (235.0 parsecs) from Earth. Light arriving here tonight left the planet around the year 1260. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 13,492,160 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 11755 b scores 0.08, ranking #4,707 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 11755
HD 11755
- Surface temperature
- 4,312 K (Sun: 5,772 K)
- Mass
- 0.72 M☉
- Radius
- 20.58 R☉
Planetary System
HD 11755 b is the only planet known to orbit HD 11755 so far.
HD 11755 b — Complete Data
| Mass (best estimate) | 1,789.38 Earth masses |
|---|---|
| Orbital period | 433.70 days |
| Orbital distance | 1.090 AU |
| Eccentricity | 0.190 |
| Earth Similarity Index | 0.08 |
| Distance from Earth | 766.6 light-years (235.0 parsecs) |
| Constellation | Cassiopeia |
| Discovery method | Radial Velocity |
| Discovery facility | Bohyunsan Optical Astronomical Observatory |
| Discovery year | 2015 |
Data: NASA Exoplanet Archive, last updated 2018-09-04. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 11755 b
Is HD 11755 b habitable?
No — HD 11755 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 11755 b?
HD 11755 b is about 767 light-years from Earth in the constellation Cassiopeia. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 13,492,160 years to get there.
How long is a year on HD 11755 b?
One orbit around HD 11755 takes 433.7 Earth days.
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