HD 2638 b
HD 2638 b is a hot Jupiter orbiting HD 2638 in the constellation Cetus. It lies about 179 light-years from Earth and was discovered in 2005 using the radial velocity method.
Is HD 2638 b in the Habitable Zone?
HD 2638 b orbits inside the inner edge of the habitable zone of HD 2638. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 2638: 0.588–1.411 AU (conservative: 0.744–1.338 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 2638 b — one full orbit around HD 2638 — lasts 3.44 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.040 AU — closer to its star than Mercury is to the Sun.
How Was HD 2638 b Discovered?
HD 2638 b was discovered in 2005 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 HD 2638 b?
HD 2638 b is 179.3 light-years (55.0 parsecs) from Earth. Light arriving here tonight left the planet around the year 1847. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 3,155,680 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 2638 b scores 0.07, ranking #5,013 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 2638
HD 2638 b belongs to a system of 3 stars; it orbits HD 2638.
HD 2638
- Surface temperature
- 5,186 K (Sun: 5,772 K)
- Mass
- 0.77 M☉
- Radius
- 0.94 R☉
Planetary System
HD 2638 b is the only planet known to orbit HD 2638 so far.
HD 2638 b — Complete Data
| Mass (best estimate) | 133.49 Earth masses |
|---|---|
| Orbital period | 3.44 days |
| Orbital distance | 0.040 AU |
| Earth Similarity Index | 0.07 |
| Distance from Earth | 179.3 light-years (55.0 parsecs) |
| Constellation | Cetus |
| Discovery method | Radial Velocity |
| Discovery facility | La Silla Observatory |
| Discovery year | 2005 |
Data: NASA Exoplanet Archive, last updated 2018-09-04. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 2638 b
Is HD 2638 b habitable?
No — HD 2638 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 2638 b?
HD 2638 b is about 179 light-years from Earth in the constellation Cetus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 3,155,680 years to get there.
How long is a year on HD 2638 b?
One orbit around HD 2638 takes 3.4 Earth days — short enough that 106 of its years would fit into one Earth year.
Explore HD 2638 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.
