HD 164509 b
HD 164509 b is a cold gas giant orbiting the G5 star HD 164509 in the constellation Ophiuchus. It lies about 173 light-years from Earth and was discovered in 2012 using the radial velocity method. It orbits within the habitable zone of its star — the region where liquid water could exist on a planet's surface.
Is HD 164509 b in the Habitable Zone?
HD 164509 b orbits within the optimistic habitable zone of HD 164509 — the broader region where liquid water might be possible under favorable atmospheric conditions.
Habitable zone of HD 164509: 0.857–2.016 AU (conservative: 1.086–1.911 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 164509 b — one full orbit around HD 164509 — lasts 280.2 Earth days, between the years of Mercury (88 days) and Earth (365 days). It orbits at an average distance of 0.870 AU — comparable to the inner Solar System. Its orbit is mildly elliptical (eccentricity 0.24).
How Was HD 164509 b Discovered?
HD 164509 b was discovered in 2012 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 164509 b?
HD 164509 b is 173.2 light-years (53.1 parsecs) from Earth. Light arriving here tonight left the planet around the year 1853. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 3,048,320 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 164509 b scores 0.35, ranking #746 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 164509
HD 164509 b belongs to a system of 2 stars; it orbits HD 164509.
HD 164509
- Spectral type
- G5
- Surface temperature
- 5,859 K (Sun: 5,772 K)
- Mass
- 1.12 M☉
- Radius
- 1.11 R☉
- Luminosity
- 1.3183 L☉
- Age
- 2.3 billion years (Sun: 4.6)
Planetary System
HD 164509 b is the only planet known to orbit HD 164509 so far.
HD 164509 b — Complete Data
| Mass (best estimate) | 140.80 Earth masses |
|---|---|
| Orbital period | 280.17 days |
| Orbital distance | 0.870 AU |
| Eccentricity | 0.238 |
| Earth Similarity Index | 0.35 |
| Distance from Earth | 173.2 light-years (53.1 parsecs) |
| Constellation | Ophiuchus |
| Discovery method | Radial Velocity |
| Discovery facility | W. M. Keck Observatory |
| Discovery year | 2012 |
Data: NASA Exoplanet Archive, last updated 2018-09-25. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 164509 b
Is HD 164509 b habitable?
HD 164509 b orbits within the habitable zone of HD 164509, the region where liquid water could exist on a planet's surface. Whether it is actually habitable depends on its atmosphere and composition, which remain unknown.
How far away is HD 164509 b?
HD 164509 b is about 173 light-years from Earth in the constellation Ophiuchus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 3,048,320 years to get there.
How long is a year on HD 164509 b?
One orbit around HD 164509 takes 280.2 Earth days.
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