HD 4732 b
HD 4732 b is a cold gas giant orbiting the K0 IV star HD 4732 in the constellation Cetus. It lies about 179 light-years from Earth and was discovered in 2012 using the radial velocity method.
Is HD 4732 b in the Habitable Zone?
HD 4732 b orbits inside the inner edge of the habitable zone of HD 4732. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 4732: 2.852–6.923 AU (conservative: 3.612–6.564 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 4732 b — one full orbit around HD 4732 — lasts 371.7 Earth days, longer than an Earth year. It orbits at an average distance of 1.129 AU. Its orbit is mildly elliptical (eccentricity 0.27).
How Was HD 4732 b Discovered?
HD 4732 b was discovered in 2012 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 4732 b?
HD 4732 b is 178.7 light-years (54.8 parsecs) from Earth. Light arriving here tonight left the planet around the year 1848. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 3,145,120 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 4732 b scores 0.15, ranking #4,183 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 4732
HD 4732 b belongs to a system of 2 stars; it orbits HD 4732.
HD 4732
- Spectral type
- K0 IV
- Surface temperature
- 4,898 K (Sun: 5,772 K)
- Mass
- 1.39 M☉
- Radius
- 5.03 R☉
- Luminosity
- 13.1299 L☉
The HD 4732 Planetary System
HD 4732 b is one of 2 known planets in the HD 4732 system. Its siblings:
- HD 4732 c (Cold Gas Giant)
HD 4732 b — Complete Data
| Mass (best estimate) | 631.21 Earth masses |
|---|---|
| Orbital period | 371.74 days |
| Orbital distance | 1.129 AU |
| Eccentricity | 0.266 |
| Earth Similarity Index | 0.15 |
| Distance from Earth | 178.7 light-years (54.8 parsecs) |
| Constellation | Cetus |
| Discovery method | Radial Velocity |
| Discovery facility | Multiple Observatories |
| Discovery year | 2012 |
Data: NASA Exoplanet Archive, last updated 2023-09-19. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 4732 b
Is HD 4732 b habitable?
No — HD 4732 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 4732 b?
HD 4732 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 3,145,120 years to get there.
How long is a year on HD 4732 b?
One orbit around HD 4732 takes 371.7 Earth days.
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