The famous "pillars of creation" - clouds of dust and gas imaged by the Hubble Space Telescope, are no more - a supernova blast wave has blown them apart. But their ghostly image will linger for another thousand years because of the time it takes for light to travel from them to Earth.
The pillars have been astronomical icons since Hubble imaged them in 1995 (scroll down for Hubble image). They are part of a larger star-forming region called the Eagle Nebula, which lies 7000 light years away. That means we are seeing the pillars as they were 7000 years ago, when the light first left them.
Now, an infrared image from the Spitzer Space Telescope has revealed a previously unseen supernova blast wave that was advancing towards the pillars at that time, threatening to ultimately sweep them away.
Nicolas Flagey of the Institut d'Astrophysique Spatiale in Orsay, France, led a team that obtained the image. It shows a cloud of hot dust thought to have been heated by a supernova blast that likely occurred between 1000 and 2000 years earlier.
Based on the cloud's position, the blast wave looked set to hit the pillars in 1000 years. Taking into account the 7000-year time lag for their light to reach the Earth, that means the pillars were actually destroyed 6000 years ago, Flagey says.
We will not see their obliteration from Earth for another 1000 years, however. And when we do, they will be in tatters - Flagey says only a few patches of the pillars are dense enough to survive the blast. "All the other parts will crumble when the shock wave arrives," he says.
Now, his team is searching through historical records to see if ancient astronomers spotted the supernova responsible for the pillars' destruction. It should have become visible on Earth 1000 to 2000 years ago, but while a few candidate events have been found in the right time frame, so far none has been confirmed as the culprit.
But Stephen Reynolds of North Carolina State University in Raleigh, US, is not convinced the hot dust cloud is the result of a supernova explosion. The expanding gas, or remnant, from the event should emit much stronger radio waves and X-rays than have been observed, he says.
"I believe that a supernova remnant less than 2000 years old at a distance of less than 6000 light years would have to have quite unusual properties to have avoided detection to this point," he told New Scientist.
Instead, he suggests that hot, high-speed winds from massive stars in the region could have heated up the dust grains in the cloud. If so, the presence of this hot gas would still erode the pillars of creation over time, he says.
The results were presented on Tuesday at a meeting of the American Astronomical Society in Seattle, Washington, US.
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