Caltech: How the Seeds of Planets Take Shape

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Caltech: How the Seeds of Planets Take Shape

Post by bystander » Thu Oct 11, 2018 5:06 pm

How the Seeds of Planets Take Shape
California Institute of Technology | 2018 Oct 10

Caltech researchers discover a new mechanism for describing planet formation, stellar winds, and more

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In theoretical research that could explain everything from planet formation to outflows from stars, to even the settling of volcanic ash, Caltech researchers have discovered a new mechanism to explain how the act of dust moving through gas leads to clumps of dust. While dust clumps were already known to play a role in seeding new planets and many other systems in space and on Earth, how the clumps formed was unknown until now.

Phil Hopkins, professor of theoretical astrophysics at Caltech, working with Jonathan (Jono) Squire, a former postdoctoral fellow at Caltech, began thinking about disturbances to dust moving through gas while studying how strong radiation from stars and galaxies drives dust-laden winds. Hopkins says that it was previously assumed that dust was stable in gas, meaning the dust grains would ride along with gas without much happening, or they would settle out of the gas if the particles were big enough, as is the case with soot from a fire.

"What Jono and I discovered is that dust and gas trying to move with one another is unstable and causes dust grains to come together," says Hopkins. "Soon we began to realize that these gas-dust instabilities are at play anywhere in the universe that a force pushes dust through gas, whether the forces are stellar winds, gravity, magnetism, or an electrical field." The team's simulations show material swirling together, with clumps of dust growing bigger and bigger. ...

The Resonant Drag Instability (RDI): Acoustic Modes ~ Philip F. Hopkins, Jonathan Squire Ubiquitous Instabilities of Dust Moving in Magnetized Gas ~ Philip F. Hopkins, Jonathan Squire Resonant Drag Instabilities in Protoplanetary Discs: The Streaming
Instability and New, Faster Growing Instabilities
~ Philip F. Hopkins, Jonathan Squire Resonant Drag Instability of Grains Streaming in Fluids ~ Philip F. Hopkins, Jonathan Squire
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