skyeye
Dust and the Helix Nebula

Dust makes this cosmic eye look red. The eerie Spitzer Space Telescope image
shows infrared radiation from the well-studied Helix Nebula (NGC 7293) a mere
700 light-years away in the constellation Aquarius. The two light-year diameter
shroud of dust and gas around a central white dwarf has long been considered an
excellent example of a planetary nebula, representing the final stages in the
evolution of a sun-like star. But the Spitzer data show the nebula's central star
itself is immersed in a surprisingly bright infrared glow. Models suggest the glow
is produced by a dust debris disk. Even though the nebular material was ejected from
the star many thousands of years ago, the close-in dust could be generated by collisions
in a reservoir of objects analogous to our own solar system's Kuiper Belt or cometary
Oort cloud. Formed in the distant planetary system, the comet-like bodies have otherwise
survived even the dramatic late stages of the star's evolution.