HD 17156
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| Observation data Epoch J2000.0 |
|
|---|---|
| Constellation (pronunciation) |
Cassiopeia |
| Right ascension | 02h 49m 44.49s |
| Declination | +71° 45′ 11.64″ |
| Apparent magnitude (V) | 8.17 |
| Absolute magnitude (V) | 3.70 |
| Distance | 255.19 ly (78.24 pc) |
| Spectral type | G0IV |
| Other designations | |
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BD+71°171, HIP 13192, SAO 4737
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HD 17156 is a star in the constellation Cassiopeia. Based on its absolute magnitude of 3.70 and spectral type of G0, it is a subgiant star, meaning this star hotter than our Sun has nearly exhausted the hydrogen supply in its core. The apparent magnitude is 8.17, which means it is not visible to the naked eye but can be seen with good binoculars. The Sun to star distance is 255.19 ly or 78.24 pc.
The mass of the star is 20% more massive and 47% larger than our Sun. Based on the chromospheric observations, it was found that the age is 110 million years older than our local star. Based on spectral observations, the star was found to be metal-rich, 74% more metals than Sol.
It is the first star in Cassiopeia around which an orbiting planet was discovered (in 2007).
In February 2008, a possible second planet (HD 17156c) was found. It was found by anomalies with the inner planet HD 17156b.
| Planet (in order from star) |
Mass (MJ) |
Orbital period (days) |
Semimajor axis (AU) |
Eccentricity |
|---|---|---|---|---|
| b | 3.111+0.035−0.015 | 21.21725+0.00048−0.00043 | 0.1594+0.0012−0.0041 | 0.6717+0.0028−0.0027 |
| c | 0.063 ± 0.007 | 111.314 ± 3 | 0.481 ± 0.001 | 0.136 ± 0.005 |
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