Pluto-Sized Objects Swarm Teenage, Sun-like Star

Astronomers have spotted an entire family of Pluto-sized objects with the help of ALMA. The tiny worlds which are swarming around an adolescent version of our own sun, may tell researchers a bit more about the evolution of solar systems.

In this case, the scientists made detailed observations of the protoplanetary disk surrounding a star known as HD 107146. They spotted an unexpected increase in the concentration of millimeter-size dust grains in the disk's outer reaches. This increase, which begins remarkably far from the host star, may actually be the result of Pluto-size worlds stirring up the region, causing smaller objects to plast themselves apart.

"The dust in HD107146 reveals this very interesting feature-it gets thicker in the very distant outer reaches of the star's disk," said Luca Ricci, one of the researchers, in a news release. "The surprising aspect is that this is the opposite of what we see in younger primordial disks where the dust is denser near the star. It is possible that we caught this particular debris disk at a stage in which Pluto-size planetesimals are forming right now in the outer disk while other Pluto-size bodies have already formed closer to the star."

It's likely that the density of dust in the outer regions of the disk is due to the presence of recently formed Pluto-size bodies. The gravity of these bodies would disturb smaller planetesimals, causing more frequently collisions that then generate the dust that ALMA spotted.

"The system offers us the chance to study an intriguing time around a young, Sun-like star," said Stuartt Corder, co-author of the new study. "We are possibly looking back in time here, back to when the sun was about two percent of its current age."

The findings reveal a bit more about this star and its system formation. This, in turn, could tell us a bit more about our own solar system.

The findings are published in the Astrophysical Journal.

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