Big Space Thing Looks Like a Moth

A moth-likestructure with a 22-billion-mile wingspan is hovering out in space.

This giantis actually a massive cloud of dust surrounding a nearby, young star imaged bythe Hubble Space Telescope that has shown astronomers that these dustdisks can take on unexpectedly unusual shapes.

Such disks aretypically flat, pancake-shaped structures where planetscan form. But HD 61005's disk breaks from the norm with a shape dubbed"The Moth". The shape is produced by starlight scattering off thedust.

"It iscompletely unexpected to find a dust disk with this unusual shape," saidsenior research scientist Dean Hines of the Space Science Institute in Corrales, New Mexico. "We think HD 61005 is plowing through a local patch ofhigher-density gas in the interstellar medium, causing material within HD61005's disk to be swept behind the star."

Hines saidthat such a collision was unexpected "because the area through which ourSun is moving was evacuated within the past few million years by at least onesupernova? Yet, here's evidence of dense material that's very close, only 100light-years away."

The Moth ispart of a survey of sun-like stars that Hines and his colleagues haveundertaken with Hubble and NASA's SpitzerSpace Telescope to study the formation and evolution of planetary systems.

Astronomershave found evidence that the environment a star forms in can influence theprospects for planet formation around it. But Hines and his team are uncertainhow passage through a cloud similar to the one HD 61005 is in would affectplanet formation.

"Whateffect this might have on the disk, and any planets forming within it, isunknown," Hines said.

Hines andhis colleagues presented their finding today at a meeting of the AmericanAstronomical Society in Austin, Texas.

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