NGC 6820

NGC 6820.

NGC 6820, an expansive emission and reflection nebula that surrounds the 7th-magnitude open cluster NGC 6823, is about 6,000 light-years away from Earth in the faint 5th-magnitude northern Vulpeculae Constellation (the Little Fox) , near M27, the Dumbbell Nebula. It is also called Sharpless catalogue Sh 2-86. The most striking feature is the trunk-like pillar of dust and gas protruding from the east side of the nebula towards the open cluster, NGC 6823 in the west. The center of the open cluster is about two million years old and is predominantly represented by many young, bright blue stars packed in a Trapezium-formed region of about 1.3 x 0.7 light-years across. Outer parts of the cluster intimately involving pillars of emission nebula NGC 6820, contain even younger stars. The huge pillars of gas and dust are probably formed when surrounding gas and dust is pushed and eroded away by radiation from nearby stars. Remarkable dark globules of gas and dust called Bok globules, are also visible in the nebula. Open star cluster NGC 6823 is about 50 light years across and forms the core of the Vulpecula OB1 stellar association.

Bok globules, named after the Dutch astronomer Bart Bok (1906-1983), who proposed their existence in the 1940′s, are dark clouds of dense cosmic dust and gas within star-forming regions in which usually star formation takes place. They most commonly result in the formation of double or multiple star systems.

Credits: Annes Astronomy News, NASA, Wikipedia.