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Deneb Algedi

Deneb Algiedi, Scheddi, Delta Capricorni, 49 Capricorni

Proper NamesDeneb Algedi, Deneb Algiedi, Scheddi
Bayer DesignationDelta Capricorni
Flamsteed Number49 Capricorni
HR (BSC)8322
Right Ascension21h 47m 2s
Declination-16° 7' 38"
Distance39 light years
12 parsecs
MagnitudeApparent: +2.8
Absolute: +2.5
Spectral ClassA7IIIm white giant
Optimum VisibilityAugust / September
NotesA close binary system, the inner two stars rapidly orbit a common centre of gravity, completing a circuit in a little over one day. The stars are oriented so that they eclipse one another on a line of sight from Earth, and as they do so, the brightness of Delta Capricorni briefly dips by nearly a quarter of a magnitude.

The constellation of Capricornus is not noted for its bright stars, but the brightest of the group is Deneb Algedi, with a visual magnitude of +2.8. It lies in the eastern part of the constellation, among the stars traditionally representing the twining fish-like tail of the star-goat, and indeed the name Deneb Algedi (sometimes spelt Deneb Algiedi) means 'tail of the goat'. The star falls close to the Ecliptic, near the point where it passes out of Capricornus and on into neighbouring Aquarius.

Deneb Algedi is a complex stellar system that lies some 39 light years from the Sun. At its heart is a white giant that has entered the later stages of its evolution, shining by fusing the helium in its core, having consumed its reserves of hydrogen. Whirling around with this giant star is a yellow-orange dwarf star, whose rapid orbit eclipses its larger companion and causes its brightness to dip regularly over a period of just over one day. Much farther out from the central star appear to be two more faint stellar companions, designated Deneb Algedi B and Deneb Algedi C.


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