A Space.com article:

www.space.com/scienceastr...is-disk.html

>"Solar Systems Warped by Interstellar Wind

By SPACE.com Staff

posted: 01 September 2009
10:56 am ET

Close encounters with interstellar gas could have given the dust-filled disks of solar systems — where planets are thought to form — the odd shapes that some of them have taken on, a new study suggests.

Stars across the galaxy have disks of dusty debris generated by the collisions of small comet- and asteroid-like bodies orbiting each star.

Astronomers have noticed that many of these debris disks are a bit wonky-looking, with lobes of dust sticking out in odd directions. One team noticed just such an oddly-shaped disk while using the Hubble Space Telescope to investigate the composition of the dust around the star HD 32297, which lies 340 light-years away from Earth in the constellation Orion.

John Debes of NASA's Goddard Space Flight Center in Greenbelt, Md., noticed that the interior portion of this star's dusty disk — a region comparable to the size of our own solar system — was warped in a way that was similar to other distant star systems.

Astronomers have previously attributed these warped shapes to the presence of undiscovered planets or past encounters with another star. But Debes and his colleagues used a model to show that the odd shapes aren't likely due to one of these exotic factors, but instead are likely caused by the interstellar environment that the star and its attendant disk are moving through.

"It's important to consider the ecology of these debris disks before running to such conclusions, and this model explains a lot of the weirdly shaped disks we see," Debes said."<