September 18, 2013
Sharpest Ever Image Of Prawn Nebula Unveiled
[ Watch the Video: Zooming In On The Prawn Nebula ]
Lee Rannals for redOrbit.com - Your Universe Online
The stellar nursery, formally known as IC 4628, sits 6,000 light-years from Earth in the constellation of Scorpius. The new image shows clumps of hot new-born stars nestled among the clouds making up the nebula.
New stars born in these gas clouds emit intense radiation, most notably in the ultraviolet spectrum; in ultraviolet light -- the same kind of radiation that causes unprotected human skin to burn when exposed to too much direct sunlight. The Earth's atmosphere shields life on the surface from most ultraviolet radiation, yet longer wavelengths are able to reach the ground, which cause tanning and sunburns. The young, hot stars in IC 4628 are emitting such radiation.
"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 colors when this process occurs, and for hydrogen the predominant color is red. IC 4628 is an example of an HII region," ESO said in a statement.
Some of the ultraviolet radiation emitted by hot stars in HII regions, or aitch-two, is at a much shorter wavelength that can ionize hydrogen. Astronomers use the term HII to refer to ionized hydrogen, and HI to refer to atomic hydrogen.
The Prawn Nebula is about 250 light-years across and covers an area of sky equivalent to four times that of a full moon. The stellar nursery is often overlooked due to its faintness and because most of its light is emitted in wavelengths which the human eye cannot see.
IC 4628 has formed numerous stars over the last few million years, both individually and in clusters. The nebula contains a large scattered star cluster named Collinder 316, which can be viewed throughout the new image taken by VLT.
Martin Pugh, an astronomer on the project, said that one of the images taken took several weeks to capture, for a total of 26 hours exposure.
The image is part of a detailed public survey of a large part of the Milky Way called VPHAS. This survey is using the power of the VLT's Survey Telescope (VST) to search for new objects like young stars and planetary nebulae. ESO said the survey will provide the best images yet of many huge glowing star formation regions.
The VST is the largest telescope in the world designed for surveying the sky in visible light. It features 32 CCD detectors that create 268-megapixel images. The Prawn Nebula image is one of the largest single images released by ESO so far.