HD 147873 b
HD 147873 b is a cold gas giant orbiting the G1 V star HD 147873 in the constellation Scorpius. It lies about 356 light-years from Earth and was discovered in 2016 using the radial velocity method.
Is HD 147873 b in the Habitable Zone?
HD 147873 b orbits inside the inner edge of the habitable zone of HD 147873. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 147873: 1.815–4.256 AU (conservative: 2.299–4.035 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 147873 b — one full orbit around HD 147873 — lasts 116.6 Earth days, between the years of Mercury (88 days) and Earth (365 days). It orbits at an average distance of 0.522 AU — comparable to the inner Solar System. Its orbit is mildly elliptical (eccentricity 0.21).
How Was HD 147873 b Discovered?
HD 147873 b was discovered in 2016 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 147873 b?
HD 147873 b is 355.7 light-years (109.1 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 6,260,320 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 147873 b scores 0.11, ranking #4,352 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 147873
HD 147873 b belongs to a system of 2 stars; it orbits HD 147873.
HD 147873
- Spectral type
- G1 V
- Surface temperature
- 5,972 K (Sun: 5,772 K)
- Mass
- 1.38 M☉
- Radius
- 2.29 R☉
- Luminosity
- 5.9900 L☉
- Age
- 4.0 billion years (Sun: 4.6)
The HD 147873 Planetary System
HD 147873 b is one of 2 known planets in the HD 147873 system. Its siblings:
- HD 147873 c (Cold Gas Giant)
HD 147873 b — Complete Data
| Mass (best estimate) | 1,633.65 Earth masses |
|---|---|
| Orbital period | 116.60 days |
| Orbital distance | 0.522 AU |
| Eccentricity | 0.207 |
| Earth Similarity Index | 0.11 |
| Distance from Earth | 355.7 light-years (109.1 parsecs) |
| Constellation | Scorpius |
| Discovery method | Radial Velocity |
| Discovery facility | Multiple Observatories |
| Discovery year | 2016 |
Data: NASA Exoplanet Archive, last updated 2016-11-09. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 147873 b
Is HD 147873 b habitable?
No — HD 147873 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 147873 b?
HD 147873 b is about 356 light-years from Earth in the constellation Scorpius. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 6,260,320 years to get there.
How long is a year on HD 147873 b?
One orbit around HD 147873 takes 116.6 Earth days.
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