CREATED BY INSEOK SONG USING MONTAGE - UCLA / GEMINI OBSERVATORY Astronomers have found evidence for the formation of young rocky planets around the star HD23514, located in the Pleiades star cluster, which is visible in the current evening sky.

Star’s dust could indicate planets

HILO » Astronomers using the Gemini North telescope on Mauna Kea believe they have found the telltale sign of rocky, Earth-like planets around a sunlike star about 400 light-years away in the Pleiades star cluster, Gemini officials announced.

That telltale clue is a large amount of hot dust circling an "adolescent" star with the designation HD23514.

"Adolescent" in this case means about 100 million years old, 45 times younger than our sun, which is 4.5 billion years old. Only one other star in the adolescent range in the entire sky is known to have lots of hot dust around it.

Both stars were discovered and investigated by a team including Joseph Rhee and Benjamin Zukerman of the University of California at Los Angeles and Inseok Song of the Spitzer Science Center.

Large, gaseous planets, like Jupiter, are believed to have been detected around distant stars by the way they make those stars wobble. The studies by Rhee and his colleagues are the first that indicate small, rocky planets like Earth.

Very young stars, perhaps 10 million years old, have lots of dust, but it blows away, clumps into planets or falls into the star by the time the star becomes an adolescent. The dust is lost in a few hundred thousand years, Rhee said.

Since HD23514 is an adolescent, it should have developed planets and lost its dust, the theory goes. The theory says hot dust is still present because two rocky planets smacked into each other relatively recently and left a lot of debris.

This is the same process that is thought to have taken place between the Earth and the moon, but in the far more distant past, more than 4 billion years ago.

"Indeed, the collision that generated the moon sent a comparable mass of debris into interplanetary orbits as is now observed in HD23514," Zukerman said.

Rounding out the similarity to the youthful stage of our own solar system is the fact that the dust around HD23514 is about the same distance from that star as the distance from the sun of our rocky planets from Mercury to Mars.

Rhee believes that the presence of the hot dust is so brief that seeing any such clues to rocky planets means there are probably many more that have passed the dust stage.