HD 40956 b
HD 40956 b is a cold gas giant orbiting HD 40956 in the constellation Camelopardalis. It lies about 380 light-years from Earth and was discovered in 2017 using the radial velocity method.
Is HD 40956 b in the Habitable Zone?
HD 40956 b orbits inside the inner edge of the habitable zone of HD 40956. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 40956: 5.354–13.015 AU (conservative: 6.782–12.339 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 40956 b — one full orbit around HD 40956 — lasts 578.6 Earth days, longer than an Earth year. It orbits at an average distance of 1.400 AU. Its orbit is mildly elliptical (eccentricity 0.24).
How Was HD 40956 b Discovered?
HD 40956 b was discovered in 2017 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 40956 b?
HD 40956 b is 380.3 light-years (116.6 parsecs) from Earth. Light arriving here tonight left the planet around the year 1646. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 6,693,280 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 40956 b scores 0.11, ranking #4,379 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 40956
HD 40956
- Surface temperature
- 4,869 K (Sun: 5,772 K)
- Mass
- 2.00 M☉
- Radius
- 8.56 R☉
- Luminosity
- 46.1700 L☉
- Age
- 1.4 billion years (Sun: 4.6)
Planetary System
HD 40956 b is the only planet known to orbit HD 40956 so far.
HD 40956 b — Complete Data
| Mass (best estimate) | 858.14 Earth masses |
|---|---|
| Orbital period | 578.60 days |
| Orbital distance | 1.400 AU |
| Eccentricity | 0.240 |
| Earth Similarity Index | 0.11 |
| Distance from Earth | 380.3 light-years (116.6 parsecs) |
| Constellation | Camelopardalis |
| Discovery method | Radial Velocity |
| Discovery facility | Multiple Observatories |
| Discovery year | 2017 |
Data: NASA Exoplanet Archive, last updated 2017-11-28. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 40956 b
Is HD 40956 b habitable?
No — HD 40956 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 40956 b?
HD 40956 b is about 380 light-years from Earth in the constellation Camelopardalis. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 6,693,280 years to get there.
How long is a year on HD 40956 b?
One orbit around HD 40956 takes 578.6 Earth days.
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