Small Planets Don't Need Stars With Heavy Metal Content To Form
Source: NASA
June 13, 2012
RELEASE : 12-197
Small Planets Don't Need Stars With Heavy Metal Content To Form
WASHINGTON -- The formation of small worlds like Earth previously was thought to occur mostly around stars rich in heavy elements such as iron and silicon. However, new ground-based observations, combined with data collected by NASA's Kepler space telescope, shows small planets form around stars with a wide range of heavy element content and suggests they may be widespread in our galaxy.
A research team led by Lars A. Buchhave, an astrophysicist at the Niels Bohr Institute and the Centre for Star and Planet Formation at the University of Copenhagen, studied the elemental composition of more than 150 stars harboring 226 planet candidates smaller than Neptune.
"I wanted to investigate whether small planets needed a special environment in order to form, like the giant gas planets, which we know preferentially develop in environments with a high content of heavy elements," said Buchhave. "This study shows that small planets do not discriminate and form around stars with a wide range of heavy metal content, including stars with only 25 percent of the sun's metallicity."
Astronomers refer to all chemical elements heavier than hydrogen and helium as metals. They define metallicity is the metal content of heavier elements in a star. Stars with a higher fraction of heavy elements than the sun are considered metal-rich. Stars with a lower fraction of heavy elements are considered metal-poor.
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Read more: http://www.nasa.gov/home/hqnews/2012/jun/HQ_12-197_AAS_KEPLER_Heavy_Metal.html
