Ed Bianchina's Astronomy



Cocoon Closeup

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Cocoon Closeup
IC 5146, also Caldwell 19, and the Sh 2-125, Cocoon Nebula, is a reflection[1]/emission[2] nebula and Caldwell object in the constellation Cygnus. IC 5146 is a star cluster and the nebula is Sh2-125. [3] It shines at magnitude +10.0[4]/+9.3[2]/+7.2.[5] Its celestial coordinates are RA 21h 53.5m, dec+47?? 16??. It is located near the naked-eye star Pi Cygni, the open cluster NGC 7209 in Lacerta, and the bright open cluster M39.[4][1] The cluster is about 4,000 ly away, and the central star that lights it formed about 100,000 years ago[6]; the nebula is about 12 arcmins across, which is equavalent to a span of 15 light years.[5] When viewing IC 5146, dark nebula Barnard 168 (B168) is an inseparable part of the experience, forming a dark lane that surrounds the cluster and projects westward forming the appearance of a trail behind the Cocoon.
Posted on September 7, 2009 Full Size| Slideshow