Beta Pictoris planet makes waves

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A giant planet is making a splash in the belt of debris orbiting the young star Beta Pictoris. Spiral waves driven by the planet whip around the dusty disk, researchers report online June 24 at arXiv.org.

Like a pebble dropped into water, the planet sends out ripples through the dust and rock surrounding Beta Pictoris each time the world plunges through the disk. The repeated disk-crossings generate spiral waves in the debris ring, astrophysicists Erika Nesvold of the University of Maryland, Baltimore County and Marc Kuchner of the NASA Goddard Space Flight Center in Greenbelt, Md., report.

Nesvold and Kuchner ran computer simulations of the system and found that the peaks and valleys of the waves concentrate dust. Their simulations show that, when viewed from Earth, the dust ripplesresemble a second disk that’s at an angle to the main disk. That finding nearly matches what astronomers actually see around Beta Pictoris, a roughly 20-million-year-old star that sits about 63 light-years away in the constellation Pictor. The waves also explain a warp in the main disk and why tiny rocky debris has mostly disappeared from its center.

Astronomers already knew about the planet around Beta Pictoris, but other stars with similarly contorted disks might have undetected planets. These simulations might help astronomers figure out what’s disturbing other debris belts, the researchers suggest, and deduce the presence of planets that would otherwise remain hidden. 

Astrophysicists Erika Nesvold and Marc Kuchner describe how their computer simulation led them to realize that the planet orbiting the star Beta Pictoris creates spiral waves in the surrounding belt of debris and that these waves can explain why the debris disk looks the way it does. Credit: NASA Goddard/YouTube