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New portrait of the
Omega Nebula


Posted: JULY 9, 2009

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A new ESO image of the Omega Nebula provides a deep and unusually wide look into a giant star-forming factory in the Milky Way.

Also known as M17, the Swan, Horseshoe or Lobster Nebula, the stellar nursery is located 5,000 light years away in the southern constellation of Sagittarius.

Three-colour composite image of the Omega Nebula. The brightly shining gas is just a blister erupting from the side of a much larger dark cloud of molecular gas from which new suns may be born. Image: ESO.

The new, near-infrared image is based on exposures obtained by the European Southern Observatory's 3.6 metre New Technology Telescope at La Silla. It reveals young and heavily dust-obscured stars, and well developed massive stars. At the left of the image a huge and strangely box-shaped cloud of dust covers the glowing gas. The beautiful array of colours results from the presence of different gases – mostly hydrogen, but also oxygen, nitrogen and sulphur – that are glowing under the fierce ultraviolet light radiated by the hot young stars.

Intense light and strong winds from the young stars have also carved out tendril-like structures in the gas and dust. The intensely thick dust originates from the remains of massive hot stars that have ended their brief lives and ejected material back into space.

The study of massive star formation is important, but difficult, since massive stars pass through the phases of stellar evolution much faster than more common low mass stars. In any case, observation of very new born stars of any mass is impossible at visible wavelengths due to heavy obscuration by the dust that cocoons these nascent stars. Fortunately, infrared and millimeter emission from these objects penetrates these dusty veils, allowing astronomers to probe the complex processes that occur during the earliest stages of stellar evolution.

Understanding the life cycle of stars provides the basis for understanding the formation and evolution of galaxies. Massive stars play a key role, with their powerful radiation fields, strong stellar winds and dramatic final interaction with the interstellar medium through supernova explosions that dominate the energetics of normal galaxies.

The Omega Nebula is one of the youngest and most massive star-forming regions in the Milky Way. Active star birth began a few million years ago and continues through today.