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Iris Nebula

C4, NGC 7023

Proper NameIris Nebula
Caldwell NumberC4
NGC/IC NumberNGC 7023
ConstellationCepheus
Right Ascension21h 1m 37s
Declination+68° 9' 48"
Distancec.1,300 light years
c.400 parsecs
MagnitudeApparent: +7.19
Absolute: -0.81
DimensionsApparent: 18' x 18'
Actual: 6.8 light years
Associated Star(s)V380 Cephei
Optimum VisibilityAugust (Usually visible from northern latitudes)

The southern regions of Cepheus border the Milky Way, and this part of space is filled with clouds and streamers of dark material. Near the point where Cepheus runs against neighbouring Draco in the west, one of these dark areas is brilliantly illuminated, creating a reflection nebula with a distinctive form, some 1,300 light years from the Solar System.

Imagery provided by Aladin sky atlas

The variable V380 Cephei is a massive young blue star that lights up the surrounding dust particles, creating a roughly circular bright nebula. This bright region contains a tracery of dark patches and dust lanes, giving the nebula a somewhat flower-like appearance, from which it takes its name. Adding to the impression is dark strand of material running away southward from the main nebula, giving the impression of a 'stalk' for the iris of the reflection nebula.

Close to the bright flower-like structure lies an open cluster, just five minutes of arc from V380 Cephei in the sky. This cluster, Collinder 427, stands out against the background of a particularly dense dark area encroaching on the nebula from the west.

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