HD 40979 b
HD 40979 b is a cold gas giant orbiting HD 40979 in the constellation Auriga. It lies about 111 light-years from Earth and was discovered in 2002 using the radial velocity method.
Is HD 40979 b in the Habitable Zone?
HD 40979 b orbits inside the inner edge of the habitable zone of HD 40979. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 40979: 1.010–2.358 AU (conservative: 1.279–2.235 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 40979 b — one full orbit around HD 40979 — lasts 264.1 Earth days, between the years of Mercury (88 days) and Earth (365 days). It orbits at an average distance of 0.850 AU — comparable to the inner Solar System. Its orbit is mildly elliptical (eccentricity 0.25).
How Was HD 40979 b Discovered?
HD 40979 b was discovered in 2002 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 40979 b?
HD 40979 b is 111.2 light-years (34.1 parsecs) from Earth. Light arriving here tonight left the planet around the year 1915. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 1,957,120 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 40979 b scores 0.31, ranking #1,183 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 40979
HD 40979 b belongs to a system of 3 stars; it orbits HD 40979.
HD 40979
- Surface temperature
- 6,165 K (Sun: 5,772 K)
- Mass
- 1.45 M☉
- Radius
- 1.21 R☉
Planetary System
HD 40979 b is the only planet known to orbit HD 40979 so far.
HD 40979 b — Complete Data
| Mass (best estimate) | 1,484.27 Earth masses |
|---|---|
| Orbital period | 264.15 days |
| Orbital distance | 0.850 AU |
| Eccentricity | 0.250 |
| Earth Similarity Index | 0.31 |
| Distance from Earth | 111.2 light-years (34.1 parsecs) |
| Constellation | Auriga |
| Discovery method | Radial Velocity |
| Discovery facility | Multiple Observatories |
| Discovery year | 2002 |
Data: NASA Exoplanet Archive, last updated 2018-09-04. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 40979 b
Is HD 40979 b habitable?
No — HD 40979 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 40979 b?
HD 40979 b is about 111 light-years from Earth in the constellation Auriga. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 1,957,120 years to get there.
How long is a year on HD 40979 b?
One orbit around HD 40979 takes 264.1 Earth days.
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