HD 12661 b
HD 12661 b is a cold gas giant orbiting HD 12661 in the constellation Aries. It lies about 123 light-years from Earth and was discovered in 2000 using the radial velocity method.
Is HD 12661 b in the Habitable Zone?
HD 12661 b orbits inside the inner edge of the habitable zone of HD 12661. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 12661: 0.866–2.049 AU (conservative: 1.097–1.942 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 12661 b — one full orbit around HD 12661 — lasts 262.7 Earth days, between the years of Mercury (88 days) and Earth (365 days). It orbits at an average distance of 0.840 AU — comparable to the inner Solar System. Its orbit is highly elliptical (eccentricity 0.38), swinging dramatically closer to and farther from its star.
How Was HD 12661 b Discovered?
HD 12661 b was discovered in 2000 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 12661 b?
HD 12661 b is 123.4 light-years (37.8 parsecs) from Earth. Light arriving here tonight left the planet around the year 1903. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 2,171,840 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 12661 b scores 0.34, ranking #823 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 12661
HD 12661
- Surface temperature
- 5,645 K (Sun: 5,772 K)
- Mass
- 1.20 M☉
- Radius
- 1.20 R☉
The HD 12661 Planetary System
HD 12661 b is one of 2 known planets in the HD 12661 system. Its siblings:
- HD 12661 c (Cold Gas Giant)
HD 12661 b — Complete Data
| Mass (best estimate) | 772.33 Earth masses |
|---|---|
| Orbital period | 262.71 days |
| Orbital distance | 0.840 AU |
| Eccentricity | 0.380 |
| Earth Similarity Index | 0.34 |
| Distance from Earth | 123.4 light-years (37.8 parsecs) |
| Constellation | Aries |
| Discovery method | Radial Velocity |
| Discovery facility | Multiple Observatories |
| Discovery year | 2000 |
Data: NASA Exoplanet Archive, last updated 2018-09-04. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 12661 b
Is HD 12661 b habitable?
No — HD 12661 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 12661 b?
HD 12661 b is about 123 light-years from Earth in the constellation Aries. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 2,171,840 years to get there.
How long is a year on HD 12661 b?
One orbit around HD 12661 takes 262.7 Earth days.
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