HJ 2814

HJ 2814 (WDS J17563-1549) is a five-star system within the Serpens constellation.

The quintuple system HJ 2814 is arranged in two subsystems: The triple system HIP 87813 (HJ 2814 A) and the binary HJ 2814 B. Those subsystems are separated by 1,600 astronomical units, and the orbital period is an estimated 26,000 years.^[10]

HIP 87813 comprises an inner binary system (Aa, with components Aa1 and Aa2) and an outer third star (Ab), which orbits the inner pair. The stars Aa1 and Aa2 are separated by 0.16 au and take 13.4 days to complete an orbit. Aa1 is an A-type main-sequence star with 2.03 times the mass of the Sun and 1.93 times the Sun's radius, while Aa2 is smaller, at 0.85 times the mass and 0.76 times the radius of the Sun. Component Ab is separated by 27 au from the inner pair and takes 70 years to complete an orbit. It has 0.77 times the mass and 0.70 times the Sun's radius. The Aa1-Aa2 pair has a close separation and can only be resolved by interferometry, while Aa-Ab are detectable with adaptive optics. Star Ab was also detected indirectly via astrometry, hence HIP 87813 is an astrometric binary.^[10] The apparent magnitude of HIP 87813 is 5.929,^[4] faintly visible to the naked eye only under ideal conditions, in dark skies.

HJ 2814 B is a pair of stars orbiting each other at an orbital period of 729 days (2.00 years).^[6] They are separated by a semi-major axis of 0.76 au^[9] and have a moderate eccentricity of 0.5.^[6] The components are named (HJ 2814) Ba and Bb, with masses of 0.94 and 0.66 times solar, respectively.^[9] The combined spectrum appears to be G0V.^[6]

Parallax measurements of the component A by the Gaia spacecraft indicate a distance of 256 light-years (78 parsecs).^[3] While the parallax listed in the Gaia database for component B is unreliable,^[5] a dynamical parallax indicates a distance of 263.5 light-years (80.8 parsecs).^[9]