When Stellar Metallicity Sparks Planet Formation
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Artist’s concept showing a young Sun-like star surrounded by a planet-forming disk of gas and dust. Image Credit: NASA/JPL-Caltech/T. Pyle
In new research, scientists have attempted to determine the precise conditions necessary for planets to form in a star system. Jarrett Johnson and Hui Li of Los Alamos National Laboratory assert that observations increasingly suggest that planet formation takes place in star systems with higher metallicities.
Astronomers use the term “metallicity” in reference to elements heavier than hydrogen and helium, such as oxygen, silicon, and iron. In the “core accretion” model of planetary formation, a rocky core gradually forms when dust grains that make up the disk of material that surrounds a young star bang into each other to create small rocks known as “planetesimals”. Citing this model, Johnson and Li stress that heavier elements are necessary to form the dust grains and planetesimals which build planetary cores.
Additionally, evidence suggests that the circumstellar disks of dust that surround young stars don’t survive as long when the stars have lower metallicities. The most likely reason for this shorter lifespan is that the light from the star causes clouds of dust to evaporate.
You can read my full Astrobiology Magazine article at: http://www.astrobio.net/exclusive/4681/when-stellar-metallicity-sparks-planet-formation
Ray Sanders is a Sci-Fi geek, astronomer and blogger. Currently researching variable stars at Arizona State University, he writes for Universe Today, The Planetary Society blog, and his own blog, Dear Astronomer
2012-12-04 08:07:39
Source: http://www.dearastronomer.com/2012/04/09/when-stellar-metallicity-sparks-planet-formation/
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