Newly formed planetesimals are responsible for the increased dust-producing activity in the outer rings of the debris disk of HD 107146. Photo by ALMA/Harvard-Smithsonian.
CAMBRIDGE, Mass., Dec. 11 (UPI) -- Researchers at Harvard have come across images that suggest a series of Pluto-sized object swarming about the outer reaches of a solar system anchored by a young star.
The Astronomers have been using the Atacama Large Millimeter/submillimeter Array (ALMA), a radio telescope in Chile, to keep tabs on star HD 107146 and the protoplanetary disk that surrounds it. Recently, the scientists noticed an uptick in the amount dust particles visible in the out rings of the disk.
In a study detailing their new observations -- soon to be published in the Astrophysical Journal -- the astronomers say the freshly kicked-up dust is evidence of the forming of new Pluto-sized planetesimals. Planetesimals are solid objects observed in a young solar system's debris disk -- big enough to affect surroundings rock, dust and gas, but not big enough to be considered a protoplanet or secure a stable orbit around its sun.
As planetesimals form theirs newly developed gravity give way to a rise in collisions, thus the uptick in dust-producing activities. Because the dust is concentrated towards the out rings of the debris disk, scientists estimate that larger protoplanets have likely already formed and stabilized closer in the sun (the dust having settled).
"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, a researcher at the Harvard-Smithsonian Center for Astrophysics (CfA), said in a recent press 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," Ricci added. "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."
The new observations by Ricci and his colleagues are significant because HD 107146 is very similar to Earth's mother star.
"This system offers us the chance to study an intriguing time around a young, Sun-like star," ALMA Deputy Director and study co-author Stuartt Corder explained. "We are possibly looking back in time here, back to when the Sun was about 2 percent of its current age."
