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l Eridani, 53 Eridani

Proper NameSceptrum
Bayer Designationl Eridani
Flamsteed Number53 Eridani
HR (BSC)1481
Right Ascension4h 38m 11s
Declination-14° 18' 14"
Distance116 light years
36 parsecs
MagnitudeApparent: +3.86
Absolute: +1.22
Spectral ClassK1.5IIIb orange giant
Optimum VisibilityDecember

A fourth-magnitude star, some 116 light years from the Sun, in the northern parts of Eridanus, Sceptrum lies southwestward of Rigel in Orion and westward of Lepus the Hare. Its Bayer designation is 'l Eridani' (that is, with a lowercase 'L' rather than an uppercase 'i'), while it is '53 Eridani' on the Flamsteed system.

The star's traditional name of Sceptrum has a curious history. This part of the sky was at one time defined as a small constellation named Sceptrum Brandenburgicum, the 'Sceptre of Brandenburg' (a 'constellation' that effectively consisted of just two stars, Sceptrum itself and HR 1483 to the north). That tentative grouping was never widely accepted, and has long been defunct, but the 'Sceptre' lived on as a name for this star, and is now officially recognised as the star's formal name.

The fainter star seen to the east (left) of Sceptrum here is HR 1487, an orange subgiant about twice as far from the Sun as Sceptrum, but separated by just seventeen arcminutes in the sky. Imagery provided by Aladin sky atlas

l Eridani is a binary system, and the name Sceptrum strictly belongs to the primary component, l Eridani A or 53 Eridani A. This primary is a red giant star and follows a mutual elliptical orbit with its companion star over a period of seventy-seven years. The spectral type of this seventh-magnitude companion star is uncertain, but in combination the entire binary system is classified as K1.5IIIb, equivalent to an orange giant.


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