HD 231701 b
HD 231701 b is a cold gas giant orbiting the F8 V star HD 231701 in the constellation Sagitta. It lies about 355 light-years from Earth and was discovered in 2007 using the radial velocity method.
Is HD 231701 b in the Habitable Zone?
HD 231701 b orbits inside the inner edge of the habitable zone of HD 231701. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 231701: 1.264–2.955 AU (conservative: 1.601–2.802 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 231701 b — one full orbit around HD 231701 — lasts 141.6 Earth days, between the years of Mercury (88 days) and Earth (365 days). It orbits at an average distance of 0.567 AU — comparable to the inner Solar System. Its orbit is mildly elliptical (eccentricity 0.13).
How Was HD 231701 b Discovered?
HD 231701 b was discovered in 2007 using the radial velocity method, with observations from W. M. Keck 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 231701 b?
HD 231701 b is 355.1 light-years (108.9 parsecs) from Earth. Light arriving here tonight left the planet around the year 1671. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 6,249,760 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 231701 b scores 0.16, ranking #4,113 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 231701
HD 231701
- Spectral type
- F8 V
- Surface temperature
- 6,101 K (Sun: 5,772 K)
- Mass
- 1.21 M☉
- Radius
- 1.53 R☉
- Luminosity
- 2.9512 L☉
- Age
- 3.4 billion years (Sun: 4.6)
Planetary System
HD 231701 b is the only planet known to orbit HD 231701 so far.
HD 231701 b — Complete Data
| Mass (best estimate) | 359.15 Earth masses |
|---|---|
| Orbital period | 141.63 days |
| Orbital distance | 0.567 AU |
| Eccentricity | 0.130 |
| Earth Similarity Index | 0.16 |
| Distance from Earth | 355.1 light-years (108.9 parsecs) |
| Constellation | Sagitta |
| Discovery method | Radial Velocity |
| Discovery facility | W. M. Keck Observatory |
| Discovery year | 2007 |
Data: NASA Exoplanet Archive, last updated 2018-09-25. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 231701 b
Is HD 231701 b habitable?
No — HD 231701 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 231701 b?
HD 231701 b is about 355 light-years from Earth in the constellation Sagitta. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 6,249,760 years to get there.
How long is a year on HD 231701 b?
One orbit around HD 231701 takes 141.6 Earth days.
Explore HD 231701 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.
