The Medusa Nebula is being seen in exquisite detail in a new image released by the European Southern Observatory. The picture was taken by astronomers using the Very Large Telescope (VLT) in Chile.
Also known as Sharpless 2-274, the Medusa Nebula is seen in the constellation of Gemini the Twins. Stretching about 4 light years in diameter, the object resides approximately 1,500 light years from our own planet. Because it is exceptionally dim, this object is difficult for astronomers to view, despite its size.
Sharpless 2-274 derives its common name from the Gorgon Medusa of Greek mythology, who possessed a head full of snakes. Red filaments of hydrogen gas in the nebula reminded some astronomers of this serpentine hair, while oxygen, seen in green, appears to form a face.
This nebula was discovered in 1955, although it was originally thought to be the remnants of a supernova. In 1971, astronomers in the Soviet Union determined it is a planetary nebula formed from gases expelled by a dying red giant star.
As stars expand and contract during their death throes, the release of gas can be intermittent, resulting in regions of dense and rarefied gases. The cloud surrounds the dying star for around 10,000 years before drifting off to space over the course of thousands of years.
"The planetary nebula stage in the life of a star is a tiny fraction of its total life span — just as the time a child takes to blow a soap bubble and see it drift away is a brief instant compared to a full human life span," the European Southern Observatory stated.
At the end of this process, all that is left behind is a tiny white dwarf, roughly the size of Earth. Powerful ultraviolet radiation blasts the surrounding material, stripping atoms of their electrons, leaving behind glowing ionized gas. The exact colors of this gas can be studied to identify the processes that formed a nebula being examined. Astronomers can also utilize filters on their telescopes to greatly increase the visibility of the gas cloud in images in an effort to understand their structure.
In the newest image, the bright star near the center is not the central core of the nebula but is a star set between the Medusa Nebula and the Earth known as TYC 776-1339-1. The stellar remnant associated with the nebula is much dimmer in the image and can be seen toward the right side of the picture.
"When the green [O III] emission from nebulae was first observed, astronomers thought they had discovered a new element that they dubbed nebulium. They later realized that it was simply a rare wavelength of radiation from an ionized form of the familiar element oxygen," European Southern Observatory officials reported.
The gas cloud that makes up the Medusa Nebula is expanding at nearly 112,000 mph, much slower than the ejection of material from a supernova.