HD 17156 b
HD 17156 b, named Mulchatna by the IAU, is an extrasolar planet approximately 255 light-years away in the constellation of Cassiopeia. The planet was discovered orbiting the yellow subgiant star HD 17156 in April 2007. The planet is classified as a relatively cool hot Jupiter planet slightly smaller than Jupiter but slightly larger than Saturn. This highly-eccentric three-week orbit takes it approximately 0.0523 AU of the star at periastron before swinging out to approximately 0.2665 AU at apastron. Its eccentricity is about the same as 16 Cygni Bb, a so-called "eccentric Jupiter". Until 2009, HD 17156 b was the transiting planet with the longest orbital period.
Size comparison of HD 17156 b with Jupiter. | |
| Discovery | |
|---|---|
| Discovered by | Fischer et al. |
| Discovery site | W. M. Keck Observatory Subaru Telescope |
| Discovery date | 14 April 2007 |
| Radial velocity and Transit | |
| Orbital characteristics | |
| 0.1589 AU (23,770,000 km) | |
| Eccentricity | 0.6768 ± 0.0034 |
| 21.2163979 ± 0.0000159 d | |
| Inclination | 86.573 ± 0.060 |
| 2454438.4835±0.0025 | |
| 121.71 ± 0.43 | |
| Semi-amplitude | 274.2 ± 2.0 |
| Star | HD 17156 |
| Physical characteristics | |
Mean radius | 1.0870 ± 0.0066 RJ |
| Mass | 3.191 ± 0.033 MJ |
Mean density | 3,470 kg/m3 (5,850 lb/cu yd) |
| 67.0 ± 2.4 m/s2 (219.8 ± 7.9 ft/s2) | |
| Temperature | ? |
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