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Astronomers find clues to early planets

KRISTIN ELVES/Arizona Daily Wildcat

Assistant professor of astronomy Michael Meyer, left, and research associate Phillip Hinz examine part of the MIRAC/BLINC infrared camera Friday afternoon inside the Steward Observatory. Last year in Chile, Meyer and Hinz were able to use the infrared camera to discover a star with characteristics similar to the sun's.

By S.M. Callimanis
Arizona Daily Wildcat
Tuesday Jan. 22, 2002

Dust around distant star found at Earth-like temperatures

Astronomers may have discovered new clues about the history of Earth in two stars located 430 light years away.

A team of scientists examining the stars - whose combined light is not visible to the naked eye - have discovered that one appears to have dust around it, "which may be a signature of planets," said Michael Meyer, University of Arizona assistant professor of astronomy.

"This system is much younger than our own solar system, so the physical characteristics are different," Meyer said. "But setting aside those differences, it could be an example of the young phase of the evolution of our solar system."

This star is hotter than our sun and has a slightly larger mass. But at Earth-like distances from the star the temperatures of the dust surrounding it are similar, Meyer said.

The dust particles that orbit the star are themselves smaller than pebbles, but they can still tell scientists a lot about the history of planetary formation.

"In order for dust to be there, huge objects probably collided there in the past," Meyer said. "So whenever we see dust, we make the inference that there must have been larger objects colliding in the past, like asteroids."

"We prefer the idea that this is happening continuously over millions of years and there are lots of objects that will continue to collide over time," Meyer said.

Because the dust surrounding the star shows a similar temperature to Earth, the find is especially significant.

However, the stars are not close enough for scientists to get a clear picture of them. Instead, a model is created based on calculations and observations from the telescope, which shows the basic structure of the star as having a disc-like structure of dust around it.

Our solar system is thought to have formed similarly, from a disc of dust-like material surrounding the sun.

Now that initial observations have been made, the next step for astronomers is to go back and use the Magellan Telescope in Las Campanas, Chile, to begin surveying hundreds of other stars.

Steward Observatory researcher Philip Hinz was involved in the building of the MIRAC/BLINC, a complex infrared camera that is part of the telescope, at the UA Mirror Lab.

Using the camera, Hinz said, the team was able to see evidence for a dust disc by looking at the radiation emitted by the star.

"Now the question is 'how common is this particular phenomenon? One in 10, one in 100 stars?'"

In August, the team will go back to Chile to make more observations with the telescope, which is among the largest and most sensitive telescopes in the world. While there, they will begin looking at hundreds of stars of different ages to learn more about the evolution of planetary systems. Using the MIRAC/BLINC camera, "we see if we can create a series of snapshots in time," Meyer said.


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