HR 8799 b
Size comparison of HR 8799 b (gray) with Jupiter. | |
| Discovery | |
|---|---|
| Discovered by | Marois et al. |
| Discovery site | Keck and Gemini observatories in Hawaii |
| Discovery date | November 13, 2008 |
| Direct imaging | |
| Orbital characteristics | |
| 71.3±0.2 AU | |
| Eccentricity | 0.017±0.002 |
| 419 years | |
| Inclination | 26.5±0.5 |
| Star | HR 8799 |
| Physical characteristics | |
| 1.10±0.03 RJ | |
| Mass | 6.0+0.4 −0.3 MJ |
Mean density | 5.041 g/cm3 |
| 104.10+0.03 −0.04 cgs | |
| Temperature | 942+12 −16 K |
| Atmosphere | |
| Composition by volume | hydrogen, water vapor, ammonia and/or acetylene, carbon dioxide, carbon monoxide, possibly with methane |
HR 8799 b is an extrasolar planet located approximately 129 light-years away in the constellation of Pegasus, orbiting the 6th magnitude Lambda Boötis star HR 8799. It has a mass of six Jupiter masses and a radius 10% larger than Jupiter's. It orbits at 71.3 AU from HR 8799 with a low ecccentricity and a period of around 419 years, being the outermost known planet in the HR 8799 system.