HD 217107

HD 217107 is a G-type main-sequence star located approximately 128 light-years away in the constellation Pisces. It is slightly more massive and luminous than the Sun. HD 217107 is of particular interest to astronomers due to the presence of multiple extrasolar planets orbiting it.

As of the last major update in astronomical databases, the HD 217107 system is known to host at least two planets: HD 217107 b and HD 217107 c.

• HD 217107 b: This was the first planet discovered in the system, a "hot Jupiter" orbiting very close to the star. It has a relatively short orbital period of about 7.1 days. Its discovery, via the radial velocity method, contributed significantly to the early understanding of exoplanetary systems and the diversity of planetary architectures.

• HD 217107 c: This planet, confirmed later, is a long-period planet residing much further away from the star. It has a significantly longer orbital period of approximately 8 years. Its presence suggests a more complex gravitational interaction within the planetary system.

The HD 217107 system continues to be a subject of study as astronomers attempt to understand the formation and evolution of planetary systems, especially those with multiple planets and diverse orbital characteristics. The star's proximity and relative brightness make it a valuable target for further observations aimed at characterizing its planets and searching for additional companions.