| Discovery | |
|---|---|
| Discovered by | Butler et al.[1] |
| Discovery site | California,USA |
| Discovery date | July 15, 2006 |
| Radial velocity | |
| Orbital characteristics | |
| 2.11 ± 0.13 AU (316,000,000 ± 19,000,000 km) | |
| Eccentricity | 0.05 ± 0.14 |
| 1155 ± 23d | |
| 2,411,100 ± 280 | |
| 195 | |
| Semi-amplitude | 7.3 ± 1.2 |
| Star | HD 164922 |
| Physical characteristics | |
| ~8R🜨 | |
| Temperature | 159 K (−114 °C; −173 °F)[2] |
HD 164922 b is anexoplanet orbiting the starHD 164922 about 72light-years from Earth in the constellationHercules. Itsinclination is not known, and itstrue mass may be significantly greater than the radial velocity lower limit of 0.36 Jupiter masses. The planet also has a low eccentricity, unlike most other long period extrasolar planets – 0.05 – about the same asJupiter andSaturn in theSolar System.[1] The exoplanet was found by using theradial velocity method, fromradial-velocity measurements via observation ofDoppler shifts in thespectrum of theplanet's parent star.
HD 164922 b is agas giant, an exoplanet that has a radius and mass around that of the planetsJupiter andSaturn. It has a temperature of 159 K (−114 °C; −173 °F).[2] It has an estimated mass of around 0.36MJ,[2] and a potential radius of around 8R🜨 based on its similar mass to Saturn.
The planet orbits a (G-type)star named HD 164922. The star has a mass of 0.87M☉ and a radius of around 0.99R☉. It has a temperature of 5293K and is 13.4 billion years old. In comparison, the Sun is about 4.6 billion years old[3] and has a temperature of 5778 K.[4] The star is metal-rich, with ametallicity ([Fe/H]) of 0.16, or 144% the solar amount. This is particularly odd for a star as old as HD 164922. Its luminosity (L☉) is 70% of the solar luminosity.[2]
The star'sapparent magnitude, or how bright it appears from Earth's perspective, is 7.01. Therefore, HD 164922 is too dim to be seen with the naked eye, but can be viewed using good binoculars.
HD 164922 b orbits its star every 1,155 days at a distance of 2.1AU (compared toMars's orbital distance from the Sun, which is around 1.5 AU). It receives only 15% of thesunlight as the Earth does from the Sun.[2]
The search for HD 164922 b started when its host star was chosen an ideal target for a planet search using theradial velocity method (in which the gravitational pull of a planet on its star is measured by observing the resultingDoppler shift), as stellar activity would not overly mask or mimicDoppler spectroscopy measurements. It was also confirmed that HD 164922 is neither a binary star nor a quickly rotating star, commonfalse positives when searching for transiting planets. Analysis of the resulting data found that the radial velocity variations most likely indicated the existence of a planet.[1] The net result was an estimate of a 12.9ME planetary companion orbiting the star at a distance of 0.33 AU with an eccentricity of 0.07.
The discovery of HD 164922 b was reported in the online archivearXiv on June 30, 2016.
