Red Star

Capture

Seestar s50 31 stacks 20 July 2026

Date

20 July 2026

Location

Camden, NSW

Original

2160 × 3840 px

DY Crucis (also known as Ruby Crucis) is one of the reddest known stars in the night sky. It lies in the constellation Crux (the Southern Cross), close to Mimosa (Beta Crucis) and is a carbon star (spectral class C). Its atmosphere is rich in carbon molecules that absorb much of the blue and green light, giving the star its remarkable deep-red colour. It has an exceptionally large B−V colour index of +5.8, making it one of the reddest stars known. Nearby Mimosa, by contrast, has a B−V colour index of −0.23 and a spectral type of B0.5 III. It is a very hot, highly luminous blue giant star. The vivid contrast between the ruby-red DY Crucis and the brilliant blue-white Mimosa is one of the most striking colour pairings in the southern sky. DY Crucis has an apparent magnitude of 8.83, making it too faint to be seen with the unaided eye but readily visible in binoculars or a small telescope under dark skies. It has a radius approximately 222 times that of the Sun.

See it in the miscellaneous gallery