Barnard's Loop (Sh 2-276)
| Barnard's Loop. Credit & copyright: W. H. Wang
(IfA, U. Hawaii)
A huge nebular shell, about 1,600 light-years away, in the
constellation Orion. It appears in photos as
a semicircular arc 14° across that envelopes a large part of the Orion
Complex and surrounds both Orion's Belt
and Orion's Sword. Though William Herschel
may have been the first to see it in 1786, its discovery is generally credited
to Edward Barnard (who called it the "Orion Loop")
who captured it on long-duration photos in 1895.
| Image credit: Steve Mandel
||R.A. 05h 31m, Dec -04° 54'
Barnard's Loop (also known as Sharpless 2-276) is thought to have been formed
by a series of supernovae that occurred
two to three million years ago (which also gave rise to several runaway
stars, including AE Aurigae, Mu Columbae
and 53 Arietis) and is kept luminous by a group of hot young stars in the
Orion OB1 Association. The ionized shell is part of an
even larger molecular hydrogen cloud measuring some 30° across.
AND STAR CLUSTERS