18 September 2013

Sharpest Image of Prawn Nebula (IC 4628) and Star Cluster Collinder 316 Imaged by the ESO



The European Southern Observatory just released the sharpest image of the Prawn Nebula (IC 4628) and the star cluster star, Collinder 316. The Prawn Nebula is 6,000 light years away in the constellation of Scorpius (The Scorpion)

A nebula is a cloud of dust and gas where stars are made. Ionized gasses such as helium and hydrogen combine with interstellar dust and start to gain mass. Over milions of years, the mass gets more dense and starts to generate heat. Once thermonuclear fusion starts a star starts to form.

The image of the Prawn Nebula was taken by the largest telescope in the world, the VLT Survey Telescope (VST). It is a 2.6-metre telescope built around the OmegaCAM camera that contains 32 CCD detectors that can 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.

This is the 1000th press release by the ESO. A milestone that started in 1985 when it featured an image of Halley's comet by the ESO 1 metre Schmidt telescope at La Silla on December 9, 1985 .

Prawn Nebula At Its Sharpest

The glowing jumble of gas clouds visible in this new image make up a huge stellar nursery nicknamed the Prawn Nebula. Taken using the VLT Survey Telescope at ESO’s Paranal Observatory in Chile, this may well be the sharpest picture ever taken of this object. It shows clumps of hot new-born stars nestled in among the clouds that make up the nebula.

Located around 6000 light-years from Earth in the constellation of Scorpius (The Scorpion), the nebula formally known as IC 4628 is a huge region filled with gas and clumps of dark dust. These gas clouds are star-forming regions, producing brilliant hot young stars. In visible light, these stars appear as a blue-white colour, but they also emit intense radiation in other parts of the spectrum — most notably in the ultraviolet (the same kind of radiation that causes skin to burn).

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 (ionised hydrogen).

Video: Prawn Nebula (IC 4628) in the constellation of Scorpius (The Scorpion)

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.

This image was taken by the VLT Survey Telescope (VST) at ESO’s Paranal Observatory in Chile. The VST is the largest telescope in the world designed for surveying the sky in visible light. It is a state-of-the-art 2.6-metre 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 picture forms part of a detailed public survey of a large part of the Milky Way called VPHAS+ (The VST/OmegaCam Photometric Hα Survey) that is using the power 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.

The very sharp VST images were further enhanced to bring out the colour by including additional high quality imaging through other filters taken by Martin Pugh, a very skilled amateur astronomer observing from Australia using 32-centimetre and 13-centimetre telescopes.

This press release represents a milestone — it is the 1000th press release issued by ESO. The first one appeared in late 1985 and featured a picture of Halley's Comet. They are all available online.

RELATED LINKS

European Southern Observatory
Comet Halley Develops a Tail
The VST/OmegaCam Photometric Hα Survey of the Southern Galactic Plane and Bulge
IC4628 - Gum 56 (or the Prawn Nebula)
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ESO Wide Field Imager Sets Its Sights On The Seagull Nebula IC-2177
European Southern Observatory Releases New Image of Pencil Nebula
Glowing Green Cell-Like Object - Nebula IC 1295 Imaged in Space
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Seagull Nebula IC 2177 Shows Off Its Wings
Largest Area Image of Carina Nebula Captured By VLT and OmegaCAM
Lobster Nebula NGC 6357 Imaged In Infrared By VISTA Telescope
Hubble's Advanced Camera for Surveys (ACS) Takes Detailed Images of Dwarf Galaxy NGC 2366 And Its Bright Nebula
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War and Peace Nebula, NGC 6357, Imaged By ESO's Very Large Telescope (VLT) In Great Detail