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Proper NameNone
Bayer Designationm Orionis
Flamsteed Number23 Orionis
Right Ascension5h 22m 50s
Declination+3° 32' 40"
Distancec.1,200 light years
c.400 parsecs
MagnitudeApparent: +5.0
Absolute: -3.4
Spectral ClassB1V Blue Dwarf
Optimum VisibilityDecember / January

A faint blue star in Orion, lying to the south of Bellatrix, the Hunter's western shoulder. With a visual magnitude of +4.99 it falls on the limit of naked eye visibility, though it is in fact a subgiant star many times the luminosity of the Sun.

More than a thousand light years from the Solar System, it lies on the fringes of the Orion Molecular Cloud, the vast dark mass of material that lies behind much of the familiar form of Orion. m Orionis lies at the heart of a multiple system, and its orbiting companions cause the brightness of the central blue star to shift slightly as viewed by an observer on Earth.


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