BD-210397 b
BD-210397 b is a cold gas giant orbiting the K7 V star BD-210397 in the constellation Cetus. It lies about 77 light-years from Earth and was discovered in 2023 using the radial velocity method.
Is BD-210397 b in the Habitable Zone?
BD-210397 b orbits beyond the outer edge of the habitable zone of BD-210397. At that distance, any surface water would almost certainly be frozen.
Habitable zone of BD-210397: 0.298–0.752 AU (conservative: 0.377–0.712 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 ›
Temperature on BD-210397 b
BD-210397 b receives 0.02 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on BD-210397 b — one full orbit around BD-210397 — lasts 1,891.0 Earth days, longer than an Earth year. It orbits at an average distance of 2.630 AU. Its orbit is mildly elliptical (eccentricity 0.10).
How Was BD-210397 b Discovered?
BD-210397 b was discovered in 2023 using the radial velocity method, with observations from La Silla 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 BD-210397 b?
BD-210397 b is 77.4 light-years (23.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1949. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 1,362,240 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. BD-210397 b scores 0.08, ranking #4,579 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: BD-210397
BD-210397
- Spectral type
- K7 V
- Surface temperature
- 4,051 K (Sun: 5,772 K)
- Mass
- 0.68 M☉
- Radius
- 0.75 R☉
- Luminosity
- 0.1350 L☉
- Age
- 6.2 billion years (Sun: 4.6)
The BD-210397 Planetary System
BD-210397 b is one of 2 known planets in the BD-210397 system. Its siblings:
- BD-210397 c (Cold Gas Giant)
BD-210397 b — Complete Data
| Mass (best estimate) | 214.00 Earth masses |
|---|---|
| Orbital period | 1,891.00 days |
| Orbital distance | 2.630 AU |
| Eccentricity | 0.100 |
| Stellar irradiation | 0.02× Earth |
| Earth Similarity Index | 0.08 |
| Distance from Earth | 77.4 light-years (23.7 parsecs) |
| Constellation | Cetus |
| Discovery method | Radial Velocity |
| Discovery facility | La Silla Observatory |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2023-06-27. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About BD-210397 b
Is BD-210397 b habitable?
No — BD-210397 b orbits outside the habitable zone of BD-210397 and is likely too cold for liquid water on its surface.
How far away is BD-210397 b?
BD-210397 b is about 77 light-years from Earth in the constellation Cetus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 1,362,240 years to get there.
How long is a year on BD-210397 b?
One orbit around BD-210397 takes 1,891.0 Earth days.
Explore BD-210397 b in the app
Browse, filter and compare 6,000+ exoplanets on iPhone, iPad and Apple Watch — with habitable-zone views, widgets and offline data.
