Using telescopes in Chile, they observed the ring of dust, known as a protoplanetary disk, around a star more than 456 light years from earth.
The high density of the dust in the northernmost part of the ring suggests planets may be forming in that dense region, they said.
"We are very surprised at the brightness of the northern side," Misato Fukagawa, a professor at Osaka University who helped to lead the research, told the Daily Telegraph.
A bright knot in the ring indicates a large amount of material has clustered in that portion, he said.
"When a sufficient amount of material is accumulated, planets or comets can be formed here," Fukugawa said.
The densest region of the ring is very distant from the star itself, roughly five times the distance between the sun and Neptune, the astronomers said.