Simulations shows how dust rings point to habitable planets

Washington, Oct 11 : Simulations developed by a NASA supercomputer have shown that dusty disks around sunlike stars point to planets that might be habitable.

The simulations show that planets nearly as small as Mars can create patterns that future telescopes may be able to detect, with the research pointing to a new avenue in the search for habitable planets.

"It may be a while before we can directly image earthlike planets around other stars but, before then, we'll be able to detect the ornate and beautiful rings they carve in interplanetary dust," said Christopher Stark, the study's lead researcher from the University of Maryland, College Park.

Working with Marc Kuchner at NASA's Goddard Space Flight Center in Greenbelt, Maryland, Stark modeled how 25,000 dust particles responded to the presence of a single planet - ranging from the mass of Mars to five times Earth's - orbiting a sunlike star.

Using NASA's Thunderhead supercomputer at Goddard, the scientists ran 120 different simulations that varied the size of the dust particles and the planet's mass and orbital distance.

"Our models use ten times as many particles as previous simulations. This allows us to study the contrast and shapes of ring structures," Kuchner said.

From this data, the researchers mapped the density, brightness, and heat signature resulting from each set of parameters.

Much of the dust in our solar system forms inward of Jupiter's orbit, as comets crumble near the sun and asteroids of all sizes collide.

The dust reflects sunlight and sometimes can be seen as a wedge-shaped sky glow - called the zodiacal light - before sunrise or after sunset.

The computer models account for the dust's response to gravity and other forces, including the star's light.

Starlight exerts a slight drag on small particles that makes them lose orbital energy and drift closer to the star.

"The particles spiral inward and then become temporarily trapped in resonances with the planet," Kuchner explained.

A resonance occurs whenever a particle's orbital period is a small-number ratio - such as two-thirds or five-sixths - of the planet's.

"The particles spiral in toward the star, get trapped in one resonance, fall out of it, spiral in some more, become trapped in another resonance, and so on," Kuchner said.

Accounting for the complex interplay of forces on tens of thousands of particles required the mathematical horsepower of a supercomputer.

The models created by Stark and Kuchner give astronomers a preview of dust structures that signal the presence of otherwise hidden worlds.

"Our catalog will help others infer a planet's mass and orbital distance, as well as the dominant particle sizes in the rings," Stark said.

ANI