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Delta Corvi, 7 Corvi

Proper NameAlgorab
Bayer DesignationDelta Corvi
Flamsteed Number7 Corvi
HR (BSC)4757
Right Ascension12h 29m 52s
Declination-16° 30' 56"
Distance87 light years
27 parsecs
MagnitudeApparent: +3.0
Absolute: +0.8
Spectral ClassB9.5V blue main sequence star
Optimum VisibilityApril
NotesAt the heart of the Algorab system is an intensely hot O-type giant star, probably surrounded by a disc of material extending out into space. The available evidence suggests that Algorab is a binary system, with an orange dwarf in a distant orbit around the primary star.

The main body of Corvus, the constellation of the Crow, is made up of a quadrangle of four stars, sandwiched between the much larger constellations of Virgo to the north and Hydra to the south. The northeastern corner of this quadrangle is marked by Algorab, the third brightest of the four stars. Its name comes from the Arabic for 'the Crow', and the name Algorab was historically also used for neighbouring Gamma Corvi, the star now more usually called Gienah (or Gienah Ghurab or Gienah Corvi).

Algorab is a hot blue-white star some eighty-seven light years from the Solar System. Its spectral type places it on the border between blue B-type and white A-type stars, and sources differ on which classification is to be preferred. The star is somewhat larger than the Sun (at some two to three times the Sun's diameter) but generates a great deal more heat and light.

The nature of the Algorab system is not completely clear, but the primary star appears to have tiny orange dwarf companion in a distant, millennia-long orbit, and there are also indications of a circumstellar disc of hot material within the system. The exceptionally slow orbit of the dwarf star (designated Algorab B) means that its identity as a binary companion to Algorab A is not yet certain, and the two stars conceivably represent an optical double rather than forming a true binary pair.


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