Astronomers spot double-layered dust disk orbiting distant star

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Washington, September 25 (ANI): By linking the twin, 10-meter telescopes in Hawaii, astronomers at the W. M. Keck Observatory discovered an extended, double-layered dust disk orbiting 51 Ophiuchi, a star that is 410 light-years from Earth.

It is the first time the Keck Interferometer Nuller instrument has identified such a compact cloud around a star so far away.

The new data suggest that 51 Ophiuchi is a protoplanetary system with a dust cloud that orbits extremely close to its parent star, according to University of Maryland astronomer Christopher Stark, who led the research team.

Keck Observatory operates one of the largest optical interferometers in the United States.

The interferometer provides high precision resolution measurements equal to a telescope as large as the distance that separates the telescope's primary mirrors - 85 meters in the case of the Keck twins.

In April 2007, the team simultaneously pointed both Keck telescopes at the star 51 Ophiuchi, or 51 Oph, and used the Interferometer's Nuller, a technique to combine the incoming light in a particular way, to block the unwanted starlight of 51 Oph and measure faint adjacent signals from the dust cloud surrounding the star.

According to the observations, excess material orbited 51 Oph.

Stark and his collaborators repeated the nulling measurements at several different wavelengths of light and combined this data with information from other telescopes to determine the shape and orientation of the material as well as the sizes of the dust grains.

The data suggest that two debris disks orbit 51 Oph.

The inner disk has larger grains, roughly 10 micrometers or larger in diameter, and extends out to four astronomical units, or AUs, beyond the star.

The second disk comprised of mainly 0.1 micrometer grains extends from roughly seven AU to 1200 AU.

"51 Oph's inner, compact dust disk is one of the most compact dust clouds ever detected, and the new Keck Interferometer Nuller observations demonstrate the instrument's ability to detect dust clouds a hundred times smaller than a conventional telescope can observe," Stark said.

His team's data also indicates that the cloud around 51 Oph is 100,000 times more dense than the dust cloud circling the Solar System. (ANI)

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