Explanation:
Why are some older stars surrounded by dust?
Observations from the
Spitzer Space Telescope by a team led by
George Rieke
(U. Arizona)
were expected to show that young stars,
on the order of one million years old, have large
dust disks, while relatively older stars,
between 10 and 100 million years old, have none.
The conventional wisdom was that the
dust disks surrounding young
stars were still forming planets, while in older systems
these disks had dissipated after planets had already formed.
Unexpectedly,
they found some older stars with the
infrared glow of impressive rings or disks of
dust.
A possible explanation is that the
old disks are remnant debris from violent collisions
between many forming planets of rock.
Resultant dust rings from such a scenario
are depicted by an artist's illustration
above.
