Credit: ESO
This image, captured by ESO’s Very Large Telescope (VLT) at Paranal,
shows a small part of the well-known emission nebula, NGC 6357,
located some 8000 light-years away, in the tail of the southern
constellation of Scorpius (The Scorpion). The image glows with the
characteristic red of an H II region, and contains a large amount of
ionised and excited hydrogen gas.
The cloud is bathed in intense ultraviolet radiation — mainly from
the open star cluster Pismis 24, home to some massive, young, blue
stars — which it re-emits as visible light, in this distinctive red
hue.
The cluster itself is out of the field of view of this picture, its
diffuse light seen illuminating the cloud on the centre-right of the
image. We are looking at a close-up of the surrounding nebula, showing a
mesh of gas, dark dust, and newly born and still forming stars.
Source: ESO
