Heavy Elements Key for Planet Formation, Study Suggests

19 April 2012 

“Planets form more commonly in star systems with relatively high concentrations of elements heavier than hydrogen and helium, a new study suggests.

Such heavier elements are necessary to form the dust grains and planetesimals that build planetary cores, according to the study, which was carried out by researchers Jarrett Johnson and Hui Li of Los Alamos National Laboratory in New Mexico.

Additionally, evidence suggests that the disks of dust that surround young stars don’t survive as long when the stars have lower concentrations of heavy elements, or lower “metallicities” in astronomers’ jargon. The most likely reason for this shorter lifespan is that light from the star causes clouds of dust to evaporate.

“Our calculation is an estimate of the minimum amount of heavy elements that must be present in circumstellar disks before planets can form,” Johnson said. “Because these heavy elements must be produced by the first stars in the universe, the first planets could only form around later generations of stars.”

Understanding how the first planets formed provides crucial information about the early universe. Additionally, a better understanding of early planetary formation impacts many facets of astronomy, including the search for life elsewhere, researchers say.”

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