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Eta Muscae

Proper NameNone
Bayer DesignationEta Muscae
Flamsteed NumberNone
HR (BSC)4993
Right Ascension13h 15m 15s
Declination-67° 53' 41"
Distance383 light years
117 parsecs
MagnitudeApparent: +4.8
Absolute: -0.6
Spectral ClassB8V blue main sequence star
Optimum VisibilityApril / May (Usually visible from southern latitudes)
NotesEta Muscae is a binary, and probably a multiple, system of young blue stars. It belongs to the Scorpius-Centaurus Association, a grouping of more than four hundred stars with shared origins that are now widely spread across the southern skies.

A faint blue star in the eastern parts of the constellation Musca, southeastward of the dark patch of the Coalsack, Eta Muscae lies on the edge of the Milky Way as it passes through Musca from Centaurus to Carina. The star has a visual magnitude of +4.8, and lies some 383 light years from the Solar System.

This star is a binary system, and possibly a multiple star. The main star as seen from Earth is in fact a spectroscopic binary, composed of two blue dwarfs in a close mutual orbit. These two stars rotate around their common centre of gravity in 2.4 days, and their proximity to one another has stretched them into ellipsoidal shapes, causing the brightness of the system to vary as they travel around one another.

There are two other candidate members of the same systemm, with one lying at least 300 AU from the main pair, and another more distant still, though at present these have yet to be definitively identified as members of the Eta Muscae system.


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