Circle of Ashes
This plot tells astronomers that a pulsar, the remnant of a stellar
explosion, is surrounded by a disk of its own ashes. The disk, revealed
by the two data points at the far right from NASA's Spitzer Space
Telescope, is the first ever found around a pulsar. Astronomers believe
planets might rise up out of these stellar ashes.
The data in this plot, or spectrum, were taken by ground-based telescopes
and Spitzer. They show that light from around the pulsar can be divided
into two categories: direct light from the pulsar, and light from the
dusty disk swirling around the pulsar. This excess light was detected by
Spitzer's infrared array camera. Dust gives off more infrared light than
the pulsar because it's cooler.
The pulsar, called 4U 0142+61, was once a massive star, until about
100,000 years ago, when it blew up in a supernova explosion and scattered
dusty debris into space. Some of that debris was captured into what
astronomers refer to as a "fallback disk," now circling the leftover
stellar core, or pulsar. The disk resembles protoplanetary disks around
young stars, out of which planets are thought to be born.
The data have been corrected to remove the effects of light scattering
from dust that lies between Earth and the pulsar.
The ground-based data is from the Keck I telescope atop Mauna Kea, Hawaii.
