A Wolf-Rayet star seen through the Keck telescope, the world's largest

April 8, 1999
Web posted at: 3:34 p.m. EDT (1934 GMT)

WASHINGTON (CNN) -- Stars are commonly though of as being round or disk-shaped, but astronomers at the Keck observatory have discovered a striking exception.

A curly-shaped star that looks like a smaller cousin of a spiral galaxy may actually be two stars engaged in a kind of courtly space dance, astronomers said.

The scientists at the University of California Berkeley were intrigued when they first spotted the star, in the direction of the constellation Sagittarius, using the Keck telescope in Hawaii a year ago.

The star is called Wolf-Rayet 104, or WR 104, and is one of a class of hot, massive, luminous stars that are much larger and brighter than our own sun.

William Danchi, one of the team at Berkeley's Space Sciences Laboratory, said the star is 4,800 light-years, or 28 million billion miles (45 million billion km), away from Earth -- too far to see using conventional telescopes.

The team adjusted the Keck telescope so it could focus on such a tiny point in the sky. It was worth the effort, Danchi said.

"This is the first time anyone has gotten any detail of a dusty Wolf-Rayet star," he said in a statement.

"Wolf-Rayet stars are so bright that they are literally flying apart," he added. This particular star smokes like a chimney, although its intense radiation should burn up the dust.

Instead, it spins out like drops of water from a lawn sprinkler, forming the spiral arcs.

How could the delicate dust particles survive such intense heat?

Writing in the journal Nature, the astronomers say they think it is because there is a second star there.

"It would seem, from the point of view of a dust flake caught between the frying pan and the fire, that two hot stars are better than one," Berkeley's Peter Tuthill said.

"When the stellar wind from the ... companion meets the wind from the Wolf-Rayet star, a shock front forms, which compresses and cools the material from the stellar winds. It is in this 'cocoon,' shielded from the direct glare of the stars, that dust formation may flourish."

The spiral is about 200 astronomical units (200 times the distance of the Earth from the sun), or 18 billion miles (30 billion km) across.

"People have always assumed that stars were spherical or disk-shaped, because they couldn't image them," Danchi said. He said the new techniques may help astronomers see all sorts of unusual-looking objects in space.

Reuters contributed to this report.

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