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Distant solar system forming from mysterious dust, scientists say 
ByEdMo   posted on01 Feb, 12 3350 Views 0 Comments Science and Technology Add to favorite

A far-off solar system seems to be forming from a strange dust whose makeup is unlike that of our and other solar systems, astronomers say.

The researchers at the University of California Los Angeles found evidence for the formation of young, rocky planets from dust circling a star some 500 light-years away. A light-year is the distance light travels in a year.

Until now, warm dust found around other stars has been very similar in composition to asteroidal or cometary material in our Solar System, said the universitys Carl Melis, who led the research while a graduate student.

But this case is different, he said.

Typically, dust debris around other stars, or our own Sun, is of the olivine, pyroxene, or silica variety, minerals commonly found on Earth, he noted. But this material is not one of these dust types. We have yet to identify what species it is.

Melis reported the findings last Wednesday at the annual American Astronomical Society meeting in Washington, D.C.

The star, known as HD 131488, appears to be surrounded by warm dust in a region called the terrestrial planet zone, where temperatures are similar to those on Earth, Melis said. He added that the dust seems to harbour rocky, embryonic planets that have recently collided.

What makes HD 131488 truly unique is the unidentified dust species released from the colliding bodies as well as the presence of cold dust far away from the star, said astronomer Benjamin Zuckerman of the university, a co-author of the research. These two characteristics make HD 131488 unlike any other star with evidence for massive quantities of dust in its terrestrial planet zone.

The researchers analyzed the warm inner dust through infrared imaging and spectroscopy using an instrument called T-ReCS on the Gemini South telescope in Chile. Spectroscopy is the analysis of the composition of objects using the spectrum of light they give off.

Artists rendering of what HD 131488 inner planetary system might look like as two large rocky bodies collide. Inset illustrates the location of HD 131488 dust belts (top) and comparable regions to our own Solar System (bottom). HD 131488 hot inner dust belt has similar separations from its host star as the terrestrial planet zone around our Sun while the stars cool dust belt has similar separations from its host star as the Kuiper Belt region in our Solar System. Also shown for our Solar System are the orbits of Jupiter, Saturn, Uranus, and Neptune. (Courtesy Gemini Observatory)

Melis and his team argue that the most plausible explanation for the unusual abundance of warm dust is a recent collision of two rocky planetary mass bodies.

While the mysterious warm dust lies at a distance from HD 131488 that is comparable to the Earth-Sun separation, the team also found cooler dust about 45 times further out. This outer dusty region is analogous to the Kuiper Belt in our own Solar System where many minor planets orbit the Sun just beyond the orbit of Neptune.

The hot dust almost certainly came from a recent catastrophic collision between two large rocky bodies in HD 131488 inner planetary system, Melis said. But the cooler dust is probably left over from planet formation that took place farther away from HD 131488.

HD 131488 lies in the direction of the constellation Centaurus and is three times heavier and 33 times more luminous than our own Sun. The star is part of a major, southern-hemisphere star forming region known as the Upper-Centaurus-Lupus association whose members are believed to be about 10 million years old. By contrast, the Sun and Earth are about 4.6 billion years old.

- Courtesy:Gemini Observatory and World Science staff

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