HD 220842 b
HD 220842 b is a cold gas giant orbiting the F8 star HD 220842 in the constellation Cassiopeia. It lies about 211 light-years from Earth and was discovered in 2016 using the radial velocity method.
Is HD 220842 b in the Habitable Zone?
The position of HD 220842 b relative to the habitable zone of HD 220842 cannot be precisely determined from the available orbital data.
Orbit and Year Length
A year on HD 220842 b — one full orbit around HD 220842 — lasts 218.5 Earth days, between the years of Mercury (88 days) and Earth (365 days). It orbits at an average distance of 0.740 AU — comparable to the inner Solar System. Its orbit is highly elliptical (eccentricity 0.40), swinging dramatically closer to and farther from its star.
How Was HD 220842 b Discovered?
HD 220842 b was discovered in 2016 using the radial velocity method, with observations from Haute-Provence 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 220842 b?
HD 220842 b is 210.9 light-years (64.6 parsecs) from Earth. Light arriving here tonight left the planet around the year 1816. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 3,711,840 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 220842 b scores 0.24, ranking #3,243 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 220842
HD 220842 b belongs to a system of 2 stars; it orbits HD 220842.
HD 220842
- Spectral type
- F8
- Surface temperature
- 5,960 K (Sun: 5,772 K)
- Mass
- 1.13 M☉
Planetary System
HD 220842 b is the only planet known to orbit HD 220842 so far.
HD 220842 b — Complete Data
| Mass (best estimate) | 1,010.70 Earth masses |
|---|---|
| Orbital period | 218.47 days |
| Orbital distance | 0.740 AU |
| Eccentricity | 0.404 |
| Earth Similarity Index | 0.24 |
| Distance from Earth | 210.9 light-years (64.6 parsecs) |
| Constellation | Cassiopeia |
| Discovery method | Radial Velocity |
| Discovery facility | Haute-Provence Observatory |
| Discovery year | 2016 |
Data: NASA Exoplanet Archive, last updated 2016-02-24. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 220842 b
Is HD 220842 b habitable?
HD 220842 b is not known to orbit within the habitable zone of HD 220842, and as a cold gas giant it is an unlikely candidate for life as we know it.
How far away is HD 220842 b?
HD 220842 b is about 211 light-years from Earth in the constellation Cassiopeia. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 3,711,840 years to get there.
How long is a year on HD 220842 b?
One orbit around HD 220842 takes 218.5 Earth days.
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