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Ras Elased Australis

Algenubi, Epsilon Leonis, 17 Leonis

Proper NamesRas Elased Australis, Algenubi
Bayer DesignationEpsilon Leonis
Flamsteed Number17 Leonis
HR (BSC)3873
Right Ascension9h 45m 51s
Declination+23° 46' 27"
Distance247 light years
76 parsecs
MagnitudeApparent: +3.0
Absolute: -1.4
Spectral ClassG1II yellow bright giant
Optimum VisibilityFebruary / March

One of the string of stars that forms the curving Sickle shape, representing the western-facing head of Leo the Lion. Ras Elased in fact means 'head of the lion', and the suffix Australis indicates that this is the southern of two stars with this name. Its counterpart, Ras Elased Borealis, is now formally known as Rasalas, and lies slightly to the north and east, where it forms the crown of the Lion's head.

Ras Elased Australis is a star in a transitional phase of its existence. Originally much hotter and bluer, its hydrogen reserves are now depleted and the star is both expanding and cooling, eventually to evolve into a red giant. As part of this transition, it is passing through a highly luminous 'bright giant' phase, emitting hundreds of times as much light as the Sun (and growing to a diameter some twenty times greater). This is a pulsating variable star, showing slight changes in its luminosity over a period of days, though the mechanism of its variability is not yet fully understood.


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