(CN) – Astronomers have learned how energy inside gaseous, dust-filled disks surrounding stars help prevent young planets from smashing into the stars they orbit, according to a study released Thursday.
Inside a star’s protoplanetary disk, dust particles cling together and, after millions of years, reach a diameter made ever larger by the star system’s planet-forming gravitational pull.
After planets form within the disk, they begin to migrate while in orbit, often drifting away from their host star or embarking on a fatal collision course with it.
In some star systems, a planet’s plunge into oblivion can take place within a million years of formation.
Scientists set out to better understand close-orbit planets uncovered by the NASA Kepler mission, in particular massive and rocky “Super-Earth” planets found in close proximity to stars.
In some star systems, these exoplanets – the term for Earth-like planets – orbit their host stars in just 10 days.
To understand the phenomena, a team of researchers led by Mario Flock of the Max Planck Institute for Astronomy in Heidelberg, Germany, simulated protoplanetary disk conditions that could produce close-orbit “Super-Earth” planets.
In a study published in the journal Astronomy & Astrophysics, the scientists said the energy protecting newborn planets is a mix of radiation and extremely hot, rapidly moving dust particles that are gasified in the ensuing heat.
The inner disk, called the silicate sublimation front, contains a heavy gas that when interacting with a planet’s thinner gas forms a dense barrier from the star, the study found.
“As a young Super-Earth travels through the gas, it is typically accompanied by gas co-rotating with the planet on an orbital path similar to a horseshoe,” the researchers said in a statement. “As the planet drifts inward and reaches the silicate sublimation front, the gas particles moving from the hot thinner gas to the denser gas outside the boundary give the planet a small kick.”
Researchers from NASA’s Jet Propulsion Laboratory in Pasadena, California, the University of Chicago and Queen Mary University in London contributed to the study.
Flock said in the statement that under the current paradigm, our solar system could also be “baby-proof,” though he added that additional research would determine whether any earth-like planets were ever suspended closer to the sun than Mercury.
“It is possible that the baby thus protected has since ‘flown the nest,’” Flock said.