Evidence of Alien Planets? No, It's Just Gas

The Fomalhaut system contains a cleared ring (shining brightly in this image) in the dust around the star. 

Scientists suspect that this gap was cleared by a pair of terrestrial planets, but new research reveals that the presence of gas could also create such a breach.

CREDIT: NASA, ESA, and P. Kalas (University of California, Berkeley)

Ring-shaped gaps in the gas around a newborn star system can trick astronomers into thinking that baby planets are forming there when they actually aren't, scientists say.

New simulations show that a sufficient concentration of gas in the disk around a young star could cause the dust to clump together to form rings, creating paths that resemble those cleared by newly formed exoplanets.

Gravity binds dust and rock together. The small clumps collect more material as they travel, eventually clearing out rings in their systems that scientists say could host alien planets.

Wladimir Lyra

These systems make good targets in the ongoing search for new worlds. But imaging such planets is a challenge because the light reflecting from them can be as much as a billion times dimmer than the light from their parent star.

"Directly imaged planets are among the hardest to find," said Wladimir Lyra, of NASA's Jet Propulsion Laboratory. "One solution is that they may simply not be there."

Planting false evidence
Spinning disks of dust and gas give rise to newborn stars. After the stars are formed, the remaining materialcan continue to collapse to create new solar systems.

"Disks start as a mixture of usually 100 times more gas than dust," Lyra told reporters. "When the star is formed, its light will slowly evaporate the gas, taking around 10 million years to dissipate it completely."

Marc Kuchner

Lyra and colleague Marc Kuchner of NASA's Goddard Space Flight Center studied how the gas and dust within these disks might interact by creating two- and three-dimensional models of such systems.

"The dust heats the gas by the photoelectric effect — an effect explained by Albert Einstein back in 1905 in a landmark paper that eventually led to the development of quantum mechanics," Lyra said.