Astronomers are intrigued by a young star with rings like Saturn's, but which are dramatically lopsided.

Perhaps the rings, made of dust and other debris, are being dragged into an elliptical orbit by the gravity of another star. Or perhaps there's a giant unseen planet in orbit around the star, dragging the disk out of round, said Paul Kalas, lead author of a study on the star.

The W.M. Keck Observatory on Mauna Kea and NASA's Hubble Space Telescope were used to study the asymmetrical disk around a star astronomers call HD 15115. Astronomers see it from the side, so the ring looks like a straight line through the center of the star, like a needle poked through a cork.

Kalas said HD 15115's rings appear to have a lot less dust than other stars in its group.

"The missing mass is quite interesting. Perhaps the mechanism which perturbed the disk into its current asymmetric morphology also shaved away a significant fraction of the mass," he said in a written statement.

The star HD15115 is believed to be about 12 million years old. It is a little larger than our sun. The star was first spotted using the Hubble Space Telescope, and detailed images were made with the Keck, whose twin mirrors gather more light than Hubble.

"The disk's needlelike shape was extremely unusual," said a press release from Keck and Hubble. "When the Keck near-infrared images were compared to the Hubble optical images, the disk was found to have an extremely blue color, which is also relatively rare among such disks."

Kalas said "the blue needle presents a host of new challenges for theorists."

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.