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Corona Australis Molecular Cloud

Corona Australis DN Complex
R Coronae Australis CO Complex

Proper NamesCorona Australis Molecular Cloud, Corona Australis DN Complex, R Coronae Australis CO Complex
Messier NumberNone
NGC/IC NumberNone
ConstellationCorona Australis, extending into Scorpius
Right Ascension19h 13m 43s
Declination-37° 27' 21"
Distance430 light years
132 parsecs
MagnitudeElements within the cloud reach an apparent magnitude of +10.00 (absolute magnitude +4.40)
DimensionsApparent: 6° 10' x 3°
Actual: 66 light years
Optimum VisibilityJuly

A vast dark cloud acting a stellar nursery, the Corona Australis Molecular Cloud has its most active regions in the northeast of Corona Australis, and spreads eastward from there into neighbouring Sagittarius. As seen from Earth, the entire cloud stretches across a strip of sky nearly seven degrees from end to end. It lies an estimated 430 light years from the Sun, making it one of the closest star-forming regions, and the entire structure extends over a region sixty-six light years across.

This image shows the most active part of the Corona Australis Molecular Cloud, which stretches far eastward of this point into the neighbouring constellation of Sagittarius. The bright star to the east (left) is Gamma Coronae Australis, which lies in the foreground of the cloud as seen from Earth. The swirling blue pattern to the west (right) is the a complex of nebulae including the R Coronae Australis Nebula, a region illuminated by young stars forming within the cloud. Imagery provided by Aladin sky atlas

The cloud contains thousands of protostars and young stars, but its strongest activity is at its western end, where it runs behind the stars Gamma and Epsilon Coronae Australis. Beyond those two stars is a darkened region designated in Bernes 157, but the dark clouds in this area are brightly illuminated in parts by newly-formed stars. Most prominent among these is R Coronae Australis, a star still in the later stages of its formation. This variable illuminates the gases around it, and as its brightness changes, the surrounding R Coronae Australis Nebula also shifts in brightness.

This busy western region is home to various interconnected nebulae and clusters. R Coronae Australis itself belongs to a group of newly-formed stars known as the Coronet Cluster, and nearby other groupings of young stars form their own reflection nebulae, notably NGC 6726 and NGC 6727 around the variable TY Coronae Australis. The same part of the sky also contains a globular cluster, NGC 6723, but this cluster is some 28,000 light years distant, and entirely unconnected to the nebulae and young clusters of the Corona Australis Molecular Cloud.


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