Astronomers spot cosmic dust fountain

February 6th, 2009 - 2:53 pm ICT by ANI  

Washington, Feb 6 (ANI): A team of astronomers has literally spotted a cosmic dust fountain in the far reaches of space, which is namely a double-star system that displays all the characteristics that are associated with dust production.

The system was found by York, the University of Toledos Adolf Witt, and their collaborators.

The double star system, designated HD 44179, sits within what astronomers call the Red Rectangle, an interstellar cloud of gas and dust (nebula) located approximately 2,300 light years from Earth.

One of the double stars is of a type that astronomers regard as a likely source of dust. These stars, unlike the sun, have already burned all the hydrogen in their cores.

Labeled post-AGB (post-asymptotic giant branch) stars, these objects collapsed after burning their initial hydrogen, until they could generate enough heat to burn a new fuel, helium.

During this transition, which takes place over tens of thousands of years, these stars lose an outer layer of their atmosphere.

Dust may form in this cooling layer, which radiation pressure coming from the stars interior pushes out the dust away from the star, along with a fair amount of gas.

In double-star systems, a disk of material from the post-AGB star may form around the second smaller, more slowly evolving star.

When disks form in astronomy, they often form jets that blow part of the material out of the original system, distributing the material in space, York explained.

This seems to be the phenomenon that Witts team observed in the Red Rectangle, probably the best example so far discovered.

The discovery has wide-ranging implications, because dust is critical to scientific theories about how stars form.

If a cloud of gas and dust collapses under its own gravity, it immediately gets hotter and starts to evaporate, York said.

Something, possibly dust, must immediately cool the cloud to prevent it from reheating.

The giant star sitting in the Red Rectangle is among those that are far too hot to allow dust condensation within their atmospheres. And yet a giant ring of dusty gas encircles it.

Our observations have shown that it is most likely the gravitational or tidal interaction between our Red Rectangle giant star and a close sun-like companion star that causes material to leave the envelope of the giant, said Witt.

Some of this material ends up in a disk of accumulating dust that surrounds that smaller companion star. Gradually, over a period of approximately 500 years, the material spirals into the smaller star. (ANI)

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