HD 171028 b
HD 171028 b is a cold gas giant orbiting HD 171028 in the constellation Ophiuchus. It lies about 364 light-years from Earth and was discovered in 2007 using the radial velocity method.
Is HD 171028 b in the Habitable Zone?
HD 171028 b orbits inside the inner edge of the habitable zone of HD 171028. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 171028: 1.797–4.246 AU (conservative: 2.276–4.026 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Orbit and Year Length
A year on HD 171028 b — one full orbit around HD 171028 — lasts 550.0 Earth days, longer than an Earth year. It orbits at an average distance of 1.320 AU. Its orbit is highly elliptical (eccentricity 0.59), swinging dramatically closer to and farther from its star.
How Was HD 171028 b Discovered?
HD 171028 b was discovered in 2007 using the radial velocity method, with observations from La Silla 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 171028 b?
HD 171028 b is 364.2 light-years (111.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1662. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 6,409,920 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 171028 b scores 0.26, ranking #2,756 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 171028
HD 171028
- Surface temperature
- 5,671 K (Sun: 5,772 K)
- Mass
- 1.53 M☉
- Radius
- 2.47 R☉
Planetary System
HD 171028 b is the only planet known to orbit HD 171028 so far.
HD 171028 b — Complete Data
| Mass (best estimate) | 832.71 Earth masses |
|---|---|
| Orbital period | 550.00 days |
| Orbital distance | 1.320 AU |
| Eccentricity | 0.590 |
| Earth Similarity Index | 0.26 |
| Distance from Earth | 364.2 light-years (111.7 parsecs) |
| Constellation | Ophiuchus |
| Discovery method | Radial Velocity |
| Discovery facility | La Silla Observatory |
| Discovery year | 2007 |
Data: NASA Exoplanet Archive, last updated 2018-09-04. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 171028 b
Is HD 171028 b habitable?
No — HD 171028 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 171028 b?
HD 171028 b is about 364 light-years from Earth in the constellation Ophiuchus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 6,409,920 years to get there.
How long is a year on HD 171028 b?
One orbit around HD 171028 takes 550.0 Earth days.
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