Gaps in dust around stars may not indicate planets as many believe

Gaps in dusty disks around young stars, thought by many astronomers to be indicative of planet formation, can occur without planets, U.S. scientists say. Wladimir Lyra at the California Institute of Technology and Marc Kuchner of NASA say interactions between dust and gas can produce some of the key patterns previously attributed to planets. Writing in the journal Nature, they said the presence of gas around a star changes the dynamics within the surrounding disk of dust in a way that can produce observed gaps without the presence of planets. They reported computer simulations suggest the interactions between dust particles and gas can organize the dust into narrow, eccentric rings, similar to the debris disk around a nearby star called Fomalhaut. The study results may explain why reports of a possible pair of planets within the Fomalhaut debris disk, assumed to be creating patterns within the disc due to their gravitational effects, have been difficult to confirm, they said.