This artist's conception shows a binary-star, or two-star, system, called
HD 113766, where astronomers suspect a rocky Earth-like planet is forming
around one of the stars. At approximately 10 to 16 million years old,
astronomers suspect this star is at just the right age for forming rocky
planets. The system is located approximately 424 light-years away from
Earth.
The two yellow spots in the image represent the system's two stars. The
brown ring of material circling closest to the central star depicts a huge
belt of dusty material, more than 100 times as much as in our asteroid
belt, or enough to build a Mars-size planet or larger. The rocky material
in the belt represents the early stages of planet formation, when dust
grains clump together to form rocks, and rocks collide to form even more
massive rocky bodies called planetesimals. The belt is located in the
middle of the system's terrestrial habitable zone, or the region around a
star where liquid water could exist on any rocky planets that might form.
Earth is located in the middle of our sun's terrestrial habitable zone.
Using NASA's Spitzer Space Telescope, astronomers learned that the belt
material in HD 113866 is more processed than the snowball-like stuff that
makes up infant solar systems and comets, which contain pristine
ingredients from the early solar system. However, it is not as processed
as the stuff found in mature planets and asteroids. This means that the
dust belt is made out of just the right mix of materials to be forming an
Earth-like planet. It is composed mainly of rocky silicates and metal
sulfides (like fool's gold), similar to the material found in lava flows.
The white outer ring shows a concentration of icy dust also detected in
the system. This material is at the equivalent position of the asteroid
belt in our solar system, but only contains about one-sixth as much
material as the inner ring. Astronomers say it is not clear from the
Spitzer observations if anything is occurring in the icy belt, but they
believe it could be a source of water later on for the planet that grows
from the inner warm ring.
