 Artist's Drawing of an Extrasolar Planet
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July 21, 2003 — Stars abundant in metals are five times more likely to harbor planets than those deficient in metals, a U.S. researcher told an international astronomy conference Monday.
The research by University of California-Berkeley astronomer Deborah Fischer has been hailed as a major aid in the search for extraterrestrial life, as it will help skywatchers scanning stars for planets able to support life narrow their search.
"I do think it's important because it's a roadmap telling us that the building blocks of metals are very important in forming planets," she said.
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"So if you bias your sample so that you're looking more at stars with heavy metals then you're going to have more chance of finding planets."
Fischer's colleague Jeff Valenti, assistant astronomer at the Space Telescope Science Institute in Baltimore, said the research offered clues into how planets formed.
"The metals are the seeds from which planets form," he said. "They're forming as little grains, little cores or particles that stick together and build up from the inside out.
"Stars forming today are much more likely to have planets than early generations of stars. It's a planetary baby boom."
The astronomers focused on five metals present on the surface of stars: iron, nickel, titanium, silicon and sodium.
After four years of analysis, they determined that the metal composition of each star showed how likely it was to be orbited by planets.
Of more than 700 stars surveyed, those with a metal profile like the sun had a five to 10 percent chance of having planets. Those with three times more metal than the sun had a 20 percent chance of having planets, while the 29 most metal-poor stars had no planets.
"Anything that helps us target our search is helpful," Search for Extraterrestrial Intelligence (SETI) scientist Ain De Horta said.
"Ten years ago we could not even identify which stars had planets; now they're coming thick and fast and increasing the likelihood of finding intelligent life."
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