Planet Formation is Child's Play

Planet Formation is Child's Play
An artist's rendition of the 1-million-year-old star system UX Tau A, located approximately 450 light-years away. Observations from NASA's Sptizer Space Telescope showed a gap in the dusty disk swirling around the system's central star. Astronomers suspect that the formation of one or multiple planets carved the space in this disk.
(Image: © NASA)

Astronomersthink they have found the two youngest solar systems ever detected, whereinfant planets could be sweeping up dust and creating voids in protoplanetarydisks 450 light-years from Earth.

NASA'sSpitzer Space Telescope observed the ring-like gaps, which could signal theearliest signs of rocky planet formation around two young stars located in theconstellation Taurus—UX Tau A and LkCa 15. Both stars are about 1 million yearsold, which is 10 times younger than other knownplanet-forming systems.

"Previously,astronomers were seeing holes at the centers of protoplanetary disks," saidCatherine Espaillat, an astronomer at the University of Michigan in Ann Arbor. Such holes are typically thought to be caused by photoevaporation, or stars burningdust away into light energy.

But insteadof central holes, Espaillat's team saw ring-like gaps in the spinning planetarymaterials.

"It'smore like a lane has been cleared within the disk. The existence of planets isthe most probable theory that can explain this structure," she said, asthe lanes are likely too distant from the star to photoevaporate.

The idea issimilar to touching a dusty record as it rotates, clearing a ring in the mat ofparticles; planets, however, use their growing gravity to sweep up the dust.

The Dec. 1issue of Astrophysical Journal Letters will detail Espaillat and hercolleagues' findings about the infant solar systems, which they said could helpexplain our own planet's past.

"Weare looking for our history," said University of Michigan astronomer Nuria Calvet, who worked with Espaillat on the research."We are looking for the history of solar systems, trying to understand howthey form."

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