53 Eridani (abbreviated 53 Eri), also designated l Eridani (l Eri), is a binary star in the constellation of Eridanus. The system has a combined

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...

of 3.87. Parallax estimates made by the '' Hipparcos'' spacecraft put it at a distance of about 110 light-years, or 33.7

parsec The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, an ...

s, from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

. The two components are designated 53 Eridani A (officially named Sceptrum) and B.

Nomenclature

''53 Eridani'' is the system's

Flamsteed designation A Flamsteed designation is a combination of a number and constellation name that uniquely identifies most naked eye stars in the modern constellations visible from southern England. They are named for John Flamsteed who first used them while co ...

; ''l Eridani'' is its Bayer designation. The designations of the two components as ''53 Eridani A'' and ''B'' derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...

(IAU). 53 Eridani bore the traditional name la, Sceptrum ('scepter'), as it was one of the brighter stars, designated "p Sceptri (Brandenburgici)", in the obsolete constellation of Sceptrum Brandenburgicum. The constellation was coined by

Gottfried Kirch Gottfried Kirch (; also KircheKenneth Glyn Jones, ''The Search for the Nebulae'', Alpha Academic, 1975, p. 19. , Kirkius; 18 December 1639 – 25 July 1710) was a German astronomer and the first "Astronomer Royal" in Berlin and, as such, directo ...

to honor the

Brandenburg province The Province of Brandenburg (german: Provinz Brandenburg) was a province of Prussia from 1815 to 1945. Brandenburg was established in 1815 from the Kingdom of Prussia's core territory, comprised the bulk of the historic Margraviate of Brandenburg ...

Prussia Prussia, , Old Prussian: ''Prūsa'' or ''Prūsija'' was a German state on the southeast coast of the Baltic Sea. It formed the German Empire under Prussian rule when it united the German states in 1871. It was ''de facto'' dissolved by an ...

, and although it was later used in other atlases by

Johann Elert Bode Johann Elert Bode (; 19 January 1747 – 23 November 1826) was a German astronomer known for his reformulation and popularisation of the Titius–Bode law. Bode determined the orbit of Uranus and suggested the planet's name. Life and career B ...

, the constellation fell out of use. In 2016, the IAU organized a

Working Group on Star Names The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education ...

(WGSN) to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name ''Sceptrum'' for the component 53 Eridani A on 30 June 2017 and it is now so included in the List of IAU-approved Star Names.

Properties

53 Eridani is a

visual binary A visual binary is a gravitationally bound binary star system that can be resolved into two stars. These stars are estimated, via Kepler's third law, to have periods ranging from a few years to thousands of years. A visual binary consists of two st ...

, where the

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...

of the two stars is calculated from their orbital motions. The primary star, 53 Eridani A, is an

evolved Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

red giant with a

spectral type In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

of K1III. It is almost ten times as wide as the Sun and slightly more massive than the Sun. The secondary star, 53 Eridani B, has an apparent magnitude of 6.95 and its spectral type is unknown. The two have an

orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...

of 77 years and have a quite eccentric orbit at 0.666. The total mass of the system is .

References

{{DEFAULTSORT:53 Eridani Eridanus (constellation) Eridani, 53 Eridani, l Sceptrum K-type giants Binary stars Durchmusterung objects 9160 029503 021594

1481 Year 1481 ( MCDLXXXI) was a common year starting on Monday (link will display the full calendar) of the Julian calendar). Events January–December * May 3 ** The 1481 Rhodes earthquake, the largest of a series, strikes the island of R ...