HPC

NASA invents super-SMACK, hallucinates WHOLE STAR SYSTEMS

31,000--core HPC sim shows Beta Pictoris b's dust cloud dancing


video Beta Pictoris, a research favourite among astro-boffins since the discovery of its bright debris-and-dust disk in 1984, has yielded new wonders in a NASA supercomputer simulation.

The debris disk, Goddard astrophysicist Marc Kuchner explains, has what looks to be a warp in long wavelengths, but looks like an X in shorter wavelengths.

“We haven't really understood until now how those patterns were created”, he said – and that's where the new simulation comes in.

Erika Nesvold (University of Maryland, Baltimore County) and Kuchner fired up Goddard's 31,000-core, Xeon E5-2697v3, 1,000 teraflop Discover supercomputer to construct a simulation (called SMACK – see below) of the interaction between the star, its disk, and the second of its planets, Beta Pictoris b.

What they've found is that the planet's motion “drives spiral waves” through the disk, and those waves result in collisions among the orbiting debris.

Those waves, in turn, might settle questions about the shape of the disk, and the presence of carbon monoxide (which doesn't last that long when exposed to UV).

As the Goddard statement explains, this suggests the strange features are the result of collisions in the disk.

To create the simulation, Nesvold and Kuchner co-developed a new modelling technique called SMACK – Superparticle-Method Algorithm for Collisions in Kuiper belts.

Nesvold and Kucnher's method tracks thousands of fragmenting particles over millions of (simulated) years. Each particle in the simulation represents “a cluster of bodies with a range of sizes and similar motions”, the Goddard release says.

The interactions of these superparticles reveal the way the trillions of fragments produce dust when they collide, and how they can be shaped into the patterns seen by telescopes like Hubble.

SMACK's “virtual Beta Pictoris” model ran for 11 days, tracking the evolution of 100,000 superparticles.

Another important datum to come out of the simulation is that it helps explain the eccentric and, as Nesvold said, “odd” orbit: “Our simulation suggests [Beta Pictoris b] arrived there about 10 million years ago, possibly after interacting with other planets orbiting the star that we haven't detected yet”.

Margaret Pan and Hanno Rein, both now at the University of Toronto, helped create the SMACK simulation.

In 2014, boffins at the ESO's Very Large Telescope were gobsmacked to work out Beta Pictoris b's rotation rate: although its ten times the size of Jupiter, it's spinning so fast that the equator whips around at nearly 100,000 km/h.

Nesvold and Kuchner discuss their findings in the video below. ®

Youtube Video

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