HD 217786
HD 217786 is a binary star system in the equatorial constellation of Pisces. With an apparent visual magnitude of 7.78, it requires binoculars or a small telescope to view. The system is located at a distance of from the Sun based on parallax, and is drifting further away with a radial velocity of +10 km/s. Kinematically, the star system belongs to the thin disk population of the Milky Way.
The primary is an F-type main-sequence star with a stellar classification of F8V. It is much older than Sun with an estimated age of 9.4 billion years and is spinning slowly with a projected rotational velocity of 1.2 km/s. The star has a lower proportion of heavy elements than the Sun, having 65% of solar abundance. It has about the same mass as the Sun but a 32% larger radius. The star is radiating nearly double the luminosity of the Sun from its photosphere at an effective temperature of 5,882 K.
A low-mass stellar companion at a projected separation of 155 AU was discovered in 2016. The proper motion of this co-moving object suggests it is gravitationally-bound to the primary, and their orbit is being viewed edge-on. If the orbit is assumed to be circular, then the orbital period for the pair is ~6.2 Myr. No other companion stars have been detected at separations from 2.74 to 76.80 AUs.
The star system exhibits strong stellar flare activity in the ultraviolet.