Ghostly Trio Tell Haunting Story of Three Stars' Deaths

A ghostly trio of planetary nebulae caught on camera by the Spitzer space telescope tell the haunting story of three stars' death.

"We look to the pictures for a sense of the history of the stars' mass loss, and to learn how they evolved over time," said Joseph Hora of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass., principal investigator of the Spitzer observing program.

Similar fates await all stars with masses roughly equivalent to the Sun. As these stars age, they run out of fuel and expand to form red giants. Eventually they slough off their outer layers, leaving the material to float away into space where it will linger for a few thousand years before fading away. Whenever ultraviolet light from the dying star's core energizes the material, it glows.

The planetary nebula PMR 1, located 5,000 light-years away in the Vela constellation, bears the nickname the "Exposed Cranium" due to its seemingly mushy insides, comprised primarily of ionized gas, and outer green shell, made up of glowing hydrogen molecules.

NGC 3242, also known as the Ghost of Jupiter, lies 1,400 light-years away in the constellation Hydra. Visible in the picture is the nebula's cooler outer halo, seen in red, and its concentric rings, created through the periodic tossing off of material as part of the star's death throes.

And located some 2,500 light-years from Earth in the Perseus constellation is NGC 650, nicknamed the Little Dumbbell. This particular nebula is unique because unlike other spherical nebulae, the Little Dumbbell boasts a butterfly shape, created by a disk of thick material running from the lower left to upper right of the image. The green and red clouds are comprised of glowing hydrogen molecules, with the green area hotter than the red.