20 Persei is a visual

binary star A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...

in the northern

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Perseus In Greek mythology, Perseus (Help:IPA/English, /ˈpɜːrsiəs, -sjuːs/; Greek language, Greek: Περσεύς, Romanization of Greek, translit. Perseús) is the legendary founder of Mycenae and of the Perseid dynasty. He was, alongside Cadmus ...

, a few degrees from

Pi Persei π Persei, Latinized as Pi Persei, is a single star in the northern constellation of Perseus. It has the traditional name Gorgonea Secunda , the second of three Gorgons in the mythology of the hero Perseus. This star has a white hue and ...

. It is visible to the naked eye as a dim, yellow-white hued point of light with a combined apparent visual magnitude of 5.343. The system is located around away from the Sun, based on its

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects ...

. It is receding from the Earth with a heliocentric

radial velocity The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the temporal rate of change, rate of change of the distance or Slant range, range between the two points. It is e ...

of +6 km/s. The orbit of the two stars has been calculated from the secondary changing its position relative to the primary. The two orbit each other every 31.6 years with an angular

semimajor axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longe ...

of 0.22 arcseconds and an eccentricity of 0.7560. The combined spectrum of 20 Persei matches that of an F-type main-sequence star, and the two stars are thought to have equal masses, 1.5 times that of the Sun. A ninth-magnitude star, designated 20 Persei C, may be associated with the pair.

References

{{DEFAULTSORT:20 Persei F-type main-sequence stars Binary stars Perseus (constellation) Durchmusterung objects Persei, 20 017904 013490 0855