In the spirit of Halloween, scientists are releasing a trio of stellar ghosts caught in infrared light by NASA's Spitzer Space Telescope. All three spooky structures, called planetary nebulas, are in fact material ejected from dying stars. As death beckoned, the stars' wispy bits and pieces were blown into outer space.
"Some might call the images haunting," said Joseph Hora of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass., principal investigator of the Spitzer observing program. "We look to the pictures for a sense of the history of the stars' mass loss, and to learn how they evolved over time."
All stars about the mass of our sun will die similarly ethereal deaths. As sun-like stars grow old, billions of years after their inception, they run out of fuel in their cores and puff up into red, giant stars, aptly named "red giants." The stars eventually cast off their outer layers, which expand away from the star. When ultraviolet light from the core of a dying star energizes the ejected layers, the billowy material glows, bringing their beautiful shapes to light.
These objects in their final death throes, the planetary nebulas, were named erroneously after their resemblance to planets by William Herschel in 1785. They come in an array of shapes, as illustrated by the three highlighted here in infrared images from Spitzer. The ghostly material will linger for only a few thousand years before ultimately fading into the dark night.