HD 203387 b
HD 203387 b is a cold gas giant orbiting HD 203387 in the constellation Capricornus. It lies about 201 light-years from Earth and was discovered in 2022 using the radial velocity method.
Is HD 203387 b in the Habitable Zone?
The position of HD 203387 b relative to the habitable zone of HD 203387 cannot be precisely determined from the available orbital data.
Orbit and Year Length
A year on HD 203387 b — one full orbit around HD 203387 — lasts 512.5 Earth days, longer than an Earth year. It orbits at an average distance of 1.771 AU. Its orbit is highly elliptical (eccentricity 0.73), swinging dramatically closer to and farther from its star.
How Was HD 203387 b Discovered?
HD 203387 b was discovered in 2022 using the radial velocity method, with observations from Multiple Observatories.
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 203387 b?
HD 203387 b is 201.4 light-years (61.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1825. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 3,544,640 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 203387 b scores 0.10, ranking #4,445 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 203387
HD 203387
- Mass
- 2.82 M☉
The HD 203387 Planetary System
HD 203387 b is one of 2 known planets in the HD 203387 system. Its siblings:
- HD 203387 c (Cold Gas Giant)
HD 203387 b — Complete Data
| Mass (best estimate) | 1,106.04 Earth masses |
|---|---|
| Orbital period | 512.54 days |
| Orbital distance | 1.771 AU |
| Eccentricity | 0.732 |
| Earth Similarity Index | 0.10 |
| Distance from Earth | 201.4 light-years (61.7 parsecs) |
| Constellation | Capricornus |
| Discovery method | Radial Velocity |
| Discovery facility | Multiple Observatories |
| Discovery year | 2022 |
Data: NASA Exoplanet Archive, last updated 2023-06-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 203387 b
Is HD 203387 b habitable?
HD 203387 b is not known to orbit within the habitable zone of HD 203387, and as a cold gas giant it is an unlikely candidate for life as we know it.
How far away is HD 203387 b?
HD 203387 b is about 201 light-years from Earth in the constellation Capricornus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 3,544,640 years to get there.
How long is a year on HD 203387 b?
One orbit around HD 203387 takes 512.5 Earth days.
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