How Are Planets Made? Scientists Just Got Closer to Explaining It

An artist's concept illustrates an icy planet-forming disk around a young star called TW Hydrae. Scientists believe they are closer to understanding how planets form. NASA/Public Domain

How is a planet born? Scientists aren't completely sure.

They know that young stars are surrounded by huge disks of dust and gas, and many researchers believe that, gradually, this material either drifts away or comes together to form into planets and asteroids.

Exactly how that happens though, isn't clear. In particular, a phenomenon called "radical drift," where drag produced by surrounding gas makes particles move towards the star, confounds easy explanations as to how the formation process would occur.

But new research, published in Astrophysical Journal Letters, sheds some light on part of the process.

A team of scientists, led by Stefan Kraus from the University of Exeter, U.K., studied the young, high temperature star V1247 Orionis, using very strong telescopes, according to a press release. The star is surrounded by just such a ring of gas and dust.

The scientists created a detailed image of the star and saw the surrounding dust disc in two parts: "a clearly defined central ring of matter and a more delicate crescent structure located further out," the statement explained.

"The region between the ring and crescent, visible as a dark strip, is thought to be caused by a young planet carving its way through the disc.

"As the planet moves around in its orbit, its motion creates areas of high pressure on either side of its path, similar to how a ship creates bow waves as it cuts through water."

The researchers theorize that these high pressure regions could protect the space where the planet is being formed: They trap in dust particles for millions of years, so that they are brought together and given time to bond and develop.

Kraus said: "The exquisite resolution of ALMA allowed us to study the intricate structure of such a dust-trapping vortex for the first time."

He explained that the dust trapping could solve the major problem with current theories of how planets form, which suggests that particles should be destroyed by drifting into the central star and be unable to grow into large forms.

"The crescent in the image constitutes a dust trap that formed at the outer edge of the dark strip. It also reveals regions of excess dust within the ring, possibly indicating a second dust trap that formed inside of the putative planet's orbit. This confirms earlier computer simulations that predicted that dust traps should form both at the outer edge and inner edge of disc gaps," he said.