Warped debris disks around stars a result of interstellar wind

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Washington, August 29 (ANI): In a new research, a team of scientists has determined that the warped shapes of the dust-filled disks where new planets may be forming around other stars, may be due to interstellar wind.

The dust-filled disks where new planets may be forming around other stars occasionally take on some difficult-to-understand shapes.

Now, a team led by John Debes at NASA's Goddard Space Flight Center in Greenbelt, Maryland, has found that a star's motion through interstellar gas can account for many of them.

"The disks contain small comet- or asteroid-like bodies that may grow to form planets," Debes said. "These small bodies often collide, which produces a lot of fine dust," he added.

As the star moves through the galaxy, it encounters thin gas clouds that create a kind of interstellar wind.

"The small particles slam into the flow, slow down, and gradually bend from their original trajectories to follow it," said Debes.

Far from being empty, the space between stars is filled with patchy clouds of low-density gas.

When a star encounters a relatively dense clump of this gas, the resulting flow produces a drag force on any orbiting dust particles.

The force only affects the smallest particles - those about one micrometer across, or about the size of particles in smoke.

"This fine dust is usually removed through collisions among the particles, radiation pressure from the star's light and other forces," explained Debes. "The drag from interstellar gas just takes them on a different journey than they otherwise would have had," he said.

Working with Alycia Weinberger at the Carnegie Institution of Washington and Goddard astrophysicist Marc Kuchner, Debes was using the Hubble Space Telescope to investigate the composition of dust around the star HD 32297, which lies 340 light-years away in the constellation Orion.

He noticed that the interior of the dusty disk - a region comparable in size to our own solar system - was warped in a way that matched a previously known warp at larger distances.

"Other research indicated there were interstellar gas clouds in the vicinity. The pieces came together to make me think that gas drag was a good explanation for what was going on," Debes said.

"It looks like interstellar gas helps young planetary systems shed dust much as a summer breeze helps dandelions scatter seeds," Kuchner said.

As dust particles respond to the interstellar wind, a debris disk can morph into peculiar shapes determined by the details of its collision with the gas cloud. (ANI)

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