Astronomy Picture of the Day

Explanation: In silhouette against a crowded star field toward the constellation Scorpius, this dusty cosmic cloud evokes for some the image of an ominous dark tower. In fact, clumps of dust and molecular gas collapsing to form stars may well lurk within the dark nebula, a structure that spans almost 40 light-years across this gorgeous telescopic portrait. Known as a cometary globule, the swept-back cloud, extending from the lower right to the head (top of the tower) left and above center, is shaped by intense ultraviolet radiation from the OB association of very hot stars in NGC 6231, off the upper edge of the scene. That energetic ultraviolet light also powers the globule's bordering reddish glow of hydrogen gas. Hot stars embedded in the dust can be seen as bluish reflection nebulae. This dark tower, NGC 6231, and associated nebulae are about 5,000 light-years away.

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
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NASA Official: Jay Norris. Specific rights apply.
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& Michigan Tech. U.

Publications with keywords: dark nebula - dust cloud - young stars - OB association
Publications with words: dark nebula - dust cloud - young stars - OB association
See also:

• NGC 6188 and NGC 6164
• The Beautiful Trifid
• Horsehead: A Wider View
• NGC 4372 and the Dark Doodad
• The Dark Tower in Scorpius
• The Pipe Nebula
• Stars and Dust Across Corona Australis

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