Astronomers have obtained one of the sharpest views ever of a vast interstellar cloud of dust and gas called Messier 17 (M17).
This WFI image shows the spectacular nebula Messier 17, also known as the Omega Nebula or the Swan Nebula. This vast region of gas, dust and hot young stars is approximately 5,920 light-years away. Image credit: ESO.
Swiss astronomer Jean Philippe de Chéseaux discovered this nebula in 1745, but his discovery did not receive widespread attention.
The object was independently rediscovered almost twenty years later by French astronomer Charles Messier, who included it as the seventeenth object in his famous astronomical catalogue.
Although officially known as Messier 17, its nicknames include: the Omega Nebula, the Swan Nebula, the Checkmark Nebula, the Horseshoe Nebula and the Lobster Nebula.
The nebula lies in the heart of our Milky Way Galaxy in the constellation of Sagittarius and is about 5,920 light-years away from us.
It spans about 15 light-years across, and its total mass is an estimated 30,000 solar masses.
Messier 17 appears as a complex red structure with some graduation to pink. Its coloring is a signature of glowing hydrogen gas.
The short-lived blue stars that recently formed in the nebula emit enough UV light to heat up surrounding gas to the extent that it begins to glow brightly.
In the central region the colors are lighter, and some parts appear white. This white color is real – it arises as a result of mixing the light from the hottest gas with the starlight reflected by dust.
The nebula also contains NGC 6618, an open star cluster of 35 stars.
The total number of stars in the nebula, however, is much higher – there are almost 800 stars in the center with even more forming in its outer regions.
Throughout this rosy glow, Messier 17 shows a web of darker regions of dust that obscure the light.
This obscuring material is also glowing and – although these areas are dark in this visible-light image – they look bright when observed using IR cameras.
This image was taken by the Wide Field Imager (WFI) instrument on the MPG/ESO 2.2-m telescope at ESO’s La Silla Observatory, Chile.
