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Adara, Epsilon Canis Majoris, 21 Canis Majoris

Proper NamesAdhara, Adara
Bayer DesignationEpsilon Canis Majoris
Flamsteed Number21 Canis Majoris
HR (BSC)2618
ConstellationCanis Major
Right Ascension6h 58m 38s
Declination-28° 58' 20"
Distance405 light years
124 parsecs
MagnitudeApparent: +1.5
Absolute: -4.0
Spectral ClassB2II blue bright giant
Optimum VisibilityJanuary
NotesWith a visual magnitude of +1.5, Adhara is among the brightest stars in the sky, comparable to Regulus in Leo or Castor in Gemini. The main blue giant star is orbited at a distance of some 900 AU by a much fainter dwarf companion.

The Epsilon star of Canis Major is Adhara (sometimes spelt Adara), southward of brilliant Sirius in the sky. Despite its 'Epsilon' designation, Adhara is actually the second brightest of the stars of Canis Major after Sirius, with an apparent magnitude of +1.5 (by comparison, Beta Canis Majoris, or Mirzam, has a rather fainter magnitude of +1.98).

Imagery provided by Aladin sky atlas

With two nearby stars, Wezen and Aludra, Adhara forms a triangular shape in the southern parts of Canis Major. Together with nearby Omicron2 Canis Majoris, these stars formed a traditional star-group known in Arabic as Al'Adhárá, 'the Virgins', from which Adhara takes its name.

Adhara is a blue supergiant more than 400 light years from the Solar System. It forms part of a binary pair, though its companion star is tiny and faint in comparison with the massive blue primary of the system.


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