Astronomers Spot a Dusty Disk Around a Young Star Actively Forming Planets

A forming planetary system has been seen for the first time. The researchers have discovered that circular gaps in a disk of dust and gas swirling around the young star, HL Tau, are actually made by forming planets.

"HL Tau likely represents the first image taken of the initial locations of planets during their formation," said Daniel Tamayo, one of the researchers, in a news release. "This could be an enormous step forward in our ability to understand how planets form."

The new image of HL Tau was taken by ALMA last October. And while those who saw the original image claimed that planets were most likely responsible for carving the gaps, some remained skeptical. These others suggested that the gaps, especially the outer three, could not represent forming planets because they were so close together. Instead, planets massive enough to carve these gaps would have been scattered violently by the force of gravity and ejected from the system early in its development.

This latest study, though, suggests that the gaps are evidence of planetary formation. This is because the gaps are separated by amounts that are consistent with what's called a special resonant configuration; in other words, these planets avoid violent collisions with each other by having specific orbital periods where they miss each other, similar to how Pluto has avoided Neptune for billions of years despite the two orbits crossing one another.

The scientists also created two videos to show how HL Tau would appear in both resonant and non-resonant configurations. In a resonant configuration, the system is far more stable.

With that said, HL Tau is a "ticking time bomb." Eventually, the planets will scatter, ejecting some and leaving the remaining bodies on elliptical orbits like the ones found around older stars.

"If further observations show these to be the typical starting conditions around other stars, it would reveal our solar system to be a remarkably special place," said Tamayo.

The findings are published in The Astrophysical Journal.

For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).