GJ 4276 b
GJ 4276 b is a Neptune-like planet orbiting the M4.0 star GJ 4276 in the constellation Cepheus. It lies about 70 light-years from Earth and was discovered in 2019 using the radial velocity method.
Is GJ 4276 b in the Habitable Zone?
GJ 4276 b orbits inside the inner edge of the habitable zone of GJ 4276. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of GJ 4276: 0.115–0.300 AU (conservative: 0.146–0.284 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 GJ 4276 b — one full orbit around GJ 4276 — lasts 13.4 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.082 AU — closer to its star than Mercury is to the Sun. Its orbit is highly elliptical (eccentricity 0.37), swinging dramatically closer to and farther from its star.
How Was GJ 4276 b Discovered?
GJ 4276 b was discovered in 2019 using the radial velocity method, with observations from Calar Alto 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 GJ 4276 b?
GJ 4276 b is 69.6 light-years (21.3 parsecs) from Earth. Light arriving here tonight left the planet around the year 1957. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 1,224,960 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. GJ 4276 b scores 0.43, ranking #391 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: GJ 4276
GJ 4276
- Spectral type
- M4.0
- Surface temperature
- 3,387 K (Sun: 5,772 K)
- Mass
- 0.41 M☉
- Radius
- 0.41 R☉
- Luminosity
- 0.0197 L☉
- Age
- 6.9 billion years (Sun: 4.6)
Planetary System
GJ 4276 b is the only planet known to orbit GJ 4276 so far.
GJ 4276 b — Complete Data
| Mass (best estimate) | 16.57 Earth masses |
|---|---|
| Orbital period | 13.35 days |
| Orbital distance | 0.082 AU |
| Eccentricity | 0.370 |
| Earth Similarity Index | 0.43 |
| Distance from Earth | 69.6 light-years (21.3 parsecs) |
| Constellation | Cepheus |
| Discovery method | Radial Velocity |
| Discovery facility | Calar Alto Observatory |
| Discovery year | 2019 |
Data: NASA Exoplanet Archive, last updated 2019-01-22. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About GJ 4276 b
Is GJ 4276 b habitable?
No — GJ 4276 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is GJ 4276 b?
GJ 4276 b is about 70 light-years from Earth in the constellation Cepheus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 1,224,960 years to get there.
How long is a year on GJ 4276 b?
One orbit around GJ 4276 takes 13.4 Earth days — short enough that 27 of its years would fit into one Earth year.
Explore GJ 4276 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.
