About 90 light-years from Earth is a star with quite a bit of company. Astronomers have discovered Pluto-size objects swarming a young star, HD 107146.
Using the Atacama Large millimeter/submillimeter Array (ALMA), the team of astronomers discovered an unexpected increase of millimeter-size dust grains around the protoplanetary disk. The distance between the young star and this increase in dust grains is vast – about 13 billion kilometers (8 billion miles).
Astronomers believe Pluto-size objects are stirring up the area and causing smaller objects to collide.
“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,” said Luca Ricci, an astronomer and lead author of the paper.
Artist concept of Pluto-size objects impacting smaller objects. Credit: A. Angelich (NRAO/AUI/NSF)
Computer models are responsible for the Pluto-size objects theory. It’s the only explanation the astronomers can come up with that would explain the dust ALMA is observing.
Data from ALMA also points to a depression in the disk far from the central star. The preliminary data suggests it is an Earth-like planet clearing debris as it orbits the star. While still early, the data could have some major implications for astronomers. Planets the size of Earth could form in orbits further out from their host star than previously thought.
Astronomers are interested in this star for a variety of reasons. “This system offers us the chance to study an intriguing time around a young, Sun-like star,” said Stuartt Corder, ALMA Deputy director and co-author of the paper. “We are possibly looking back in time here, back to when the Sun was about 2 percent of its current age.”
Scientists are also observing a solar system in transition. They are watching a system transition from its early stage protoplanetary disk into something more akin to our own solar system.