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M17 - the Omega nebulae - Widefield

Short object description

The nebula with the number 17 in the constellation Sagittarius, catalogued by Charles Messier, is also known as the Omega or Horseshoe Nebula because of its characteristic dark cloud at the right edge. If the image is rotated by 180 degrees, a celestial swan can be seen in the brightest part of the nebula. Thus M 17 is also known as Schwannebel.

The active star forming region is about 5500 light years away from Earth and is located almost exactly on the galactic equator. The diameter of the nebula is 15 light years, so it appears in the sky about as large as the moon.

Hundreds of newly formed stars have been discovered inside M 17, but they are still hiding behind the dense gas clouds and only reveal themselves through their infrared radiation. The gas in the nebula is estimated to have more than 30,000 times the mass of the sun. The nebula also contains an open star cluster of 35 stars called NGC 6618, but the total number of stars in the nebula is much higher - there are almost 800 stars in the centre and even more are forming in the outer regions.

On the right above the Omegan Nebula there are two more small emission nebulae, IC 4706 and IC 4707. Southwest of M17 (lower right of the image) is part of the very large H-II region IC 4701 in which the open star cluster (type III 2 m) is embedded.Translated with (free version)
The nebula was discovered around 1745 by the Swiss astronomer Jean-Philippe Loys de Chéseaux.

Early observers were uncertain whether M17 was a gas cloud or a star cluster too far away from Earth to be resolved into individual stars. Only in 1866 the true physical structure could be clarified by William Huggins. With a newly developed instrument, the astronomical spectrograph, he was able to prove that the Omega Nebula is a cloud of glowing gas.

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