HD 221420 b
HD 221420 b is a exoplanet orbiting the G2 IV-V star HD 221420 in the constellation Octans. It lies about 102 light-years from Earth and was discovered in 2019 using the radial velocity method.
Is HD 221420 b in the Habitable Zone?
HD 221420 b orbits beyond the outer edge of the habitable zone of HD 221420. At that distance, any surface water would almost certainly be frozen.
Habitable zone of HD 221420: 1.496–3.519 AU (conservative: 1.895–3.336 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Orbit and Year Length
A year on HD 221420 b — one full orbit around HD 221420 — lasts 10,090.0 Earth days, longer than Jupiter's 12-year orbit. It orbits at an average distance of 10.150 AU. Its orbit is mildly elliptical (eccentricity 0.14).
How Was HD 221420 b Discovered?
HD 221420 b was discovered in 2019 using the radial velocity method, with observations from Anglo-Australian Telescope.
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 221420 b?
HD 221420 b is 101.6 light-years (31.1 parsecs) from Earth. Light arriving here tonight left the planet around the year 1925. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 1,788,160 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 221420 b scores 0.11, ranking #4,355 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 221420
HD 221420
- Spectral type
- G2 IV-V
- Surface temperature
- 5,847 K (Sun: 5,772 K)
- Mass
- 1.35 M☉
- Radius
- 1.95 R☉
- Luminosity
- 4.0080 L☉
- Age
- 3.7 billion years (Sun: 4.6)
Planetary System
HD 221420 b is the only planet known to orbit HD 221420 so far.
HD 221420 b — Complete Data
| Mass | 7,278.27 Earth masses (22.900 Jupiter masses) |
|---|---|
| Orbital period | 10,090.00 days |
| Orbital distance | 10.150 AU |
| Eccentricity | 0.140 |
| Earth Similarity Index | 0.11 |
| Distance from Earth | 101.6 light-years (31.1 parsecs) |
| Constellation | Octans |
| Discovery method | Radial Velocity |
| Discovery facility | Anglo-Australian Telescope |
| Discovery year | 2019 |
Data: NASA Exoplanet Archive, last updated 2021-07-26. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 221420 b
Is HD 221420 b habitable?
No — HD 221420 b orbits outside the habitable zone of HD 221420 and is likely too cold for liquid water on its surface.
How far away is HD 221420 b?
HD 221420 b is about 102 light-years from Earth in the constellation Octans. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 1,788,160 years to get there.
How long is a year on HD 221420 b?
One orbit around HD 221420 takes 10,090.0 Earth days.
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