HD 220197 b
HD 220197 b is a cold gas giant orbiting HD 220197 in the constellation Pegasus. It lies about 210 light-years from Earth and was discovered in 2018 using the radial velocity method.
Is HD 220197 b in the Habitable Zone?
HD 220197 b orbits beyond the outer edge of the habitable zone of HD 220197. At that distance, any surface water would almost certainly be frozen.
Habitable zone of HD 220197: 0.716–1.690 AU (conservative: 0.906–1.602 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 220197 b — one full orbit around HD 220197 — lasts 1,728.0 Earth days, longer than an Earth year. It orbits at an average distance of 2.729 AU. Its orbit is mildly elliptical (eccentricity 0.19).
How Was HD 220197 b Discovered?
HD 220197 b was discovered in 2018 using the radial velocity method, with observations from Roque de los Muchachos 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 220197 b?
HD 220197 b is 210.1 light-years (64.4 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 3,697,760 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 220197 b scores 0.22, ranking #3,706 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 220197
HD 220197
- Surface temperature
- 5,683 K (Sun: 5,772 K)
- Mass
- 0.91 M☉
- Radius
- 0.98 R☉
- Age
- 10.2 billion years (Sun: 4.6)
Planetary System
HD 220197 b is the only planet known to orbit HD 220197 so far.
HD 220197 b — Complete Data
| Mass (best estimate) | 63.57 Earth masses |
|---|---|
| Orbital period | 1,728.00 days |
| Orbital distance | 2.729 AU |
| Eccentricity | 0.187 |
| Earth Similarity Index | 0.22 |
| Distance from Earth | 210.1 light-years (64.4 parsecs) |
| Constellation | Pegasus |
| Discovery method | Radial Velocity |
| Discovery facility | Roque de los Muchachos Observatory |
| Discovery year | 2018 |
Data: NASA Exoplanet Archive, last updated 2019-11-18. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 220197 b
Is HD 220197 b habitable?
No — HD 220197 b orbits outside the habitable zone of HD 220197 and is likely too cold for liquid water on its surface.
How far away is HD 220197 b?
HD 220197 b is about 210 light-years from Earth in the constellation Pegasus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 3,697,760 years to get there.
How long is a year on HD 220197 b?
One orbit around HD 220197 takes 1,728.0 Earth days.
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