The Prawn Nebula — an enormous star-birthing nebula located in the constellation of Scorpius — has been beautifully captured in a new image taken by the VLT Survey Telescope at ESO’s Paranal Observatory in Chile. The striking new image is very likely the sharpest image ever taken of the stellar nursery — depicting in great detail, the very hot, gathering of new-born stars buried amongst the dust clouds that the nebula is composed of.
The Prawn Nebula is located about 6000 light-years from the Earth, in the Scorpion constellation. The famous nebula is known, on a more formally level, as IC 4628. In visible light, the very hot stars burn a blue-white color, but they also emit a great deal of very intense radiation in other parts of the spectrum, especially in the ultraviolet.
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It is this ultraviolet light from the stars that causes the gas clouds to glow. This radiation strips electrons from hydrogen atoms, which then later recombine and release energy in the form of light. Each chemical element emits light at characteristic colours when this process occurs, and for hydrogen the predominant colour is red. IC 4628 is an example of an HII region.
The Prawn Nebula is around 250 light-years across, covering an area of sky equivalent to four times that of the full Moon. Despite this huge size it has been often overlooked by observers due to its faintness and because most of its light is emitted at wavelengths where the human eye is not sensitive. The nebula is also known as Gum 56, after the Australian astronomer Colin Gum, who published a catalogue of HII regions in 1955.
Over the last few million years this region of sky has formed many stars, both individually and in clusters. There is a large scattered star cluster named Collinder 316 which extends over most of this image. This cluster is a part of a much larger gathering of very hot and luminous stars. Also visible are many dark structures or cavities, where interstellar matter has been blown away by the powerful winds generated by the nearby hot stars.
The telescope that obtained the new image — the VLT Survey Telescope (VST) at ESO’s Paranal Observatory in Chile — is the biggest telescope in the world, as far as telescopes designed for surveying the sky in visible light go anyways. “It is a state-of-the-art 2.6-meter telescope built around the OmegaCAM camera that contains 32 CCD detectors that together create 268-megapixel images. This new 24 000-pixel-broad image is a mosaic of two such images and is one of the largest single images released by ESO so far.”
The new image is part of a detailed public survey of a large portion of the Milky Way that is currently being undertaken — dubbed VPHAS+, this survey is utilizing the abilities of the VST to “search for new objects such as young stars and planetary nebulae. The survey will also provide the best images yet taken of many huge glowing star formation regions, such as the one pictured here”.