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Yed Prior

Delta Ophiuchi, 1 Ophiuchi

Proper NameYed Prior
Bayer DesignationDelta Ophiuchi
Flamsteed Number1 Ophiuchi
HR (BSC)6056
Right Ascension16h 14m 21s
Declination-3° 41' 40"
Distance171 light years
52 parsecs
MagnitudeApparent: +2.8
Absolute: -0.8
Spectral ClassM0.5III Red Giant
Optimum VisibilityJune
NotesYed Prior is a metal-rich red giant star in the later stages of its evolution. The hydrogen in its core has been depleted, and its outer shell has expanded to a diameter nearly sixty times that of the Sun, though the resulting giant star is much less dense than a dwarf star like the Sun.

This variable red giant lies very close to Ophiuchus' border with neighbouring Serpens Caput. About one degree 'behind' it as it travels across the sky is another giant, Yed Posterior. While these two appear to be close companions, they are in fact some seventy light years apart.


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