An entire family of Pluto-sized protoplanets may be swarming around a young star known as HD 107146, an adolescent version of our own Sun, a new study says.

Found using the Atacama Large Millimeter/submillimeter Array (ALMA), large concentrations of millimeter-sized dust grains were seen in the disk's outer reaches, a find that surprised scientists. Especially considering that the objects are located in the far reaches of its host star - a whopping 13 billion kilometers away.

Dust in debris disks typically consists of material left over from the formation of planets. In a disk's early years, there is an abundance of dust due to collisions with comets and asteroids, whereas mature solar systems with fully formed planets have little dust remaining.

"The dust in HD 107146 reveals this very interesting feature - it gets thicker in the very distant outer reaches of the star's disk," lead study author Luca Ricci, an astronomer at the Harvard-Smithsonian Center for Astrophysics (CfA), said in a statement.

According to certain computer models, this unique observation can only be explained by the presence of Pluto-sized planetismals, which cause smaller objects to collide and blast themselves apart.

"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," Ricci added.

The star HD 107146 is located approximately 90 light-years from Earth and is approximately 100 million years old. Astronomers find it of particular interest given that it is in many ways a younger version of our own Sun, and essentially provides a window for looking back in time to when our own Sun was just growing up.

The findings were published in The Astrophysical Journal.

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