The researchers said that nothing like it had ever been spotted around a star.
They believe the star, known as Mira, will help them to study what happens as
stars meet their demise.
Mark Seibert, a co-author of the paper, which was published in the journal
Nature, and a scientist at the Carnegie Observatories in Pasadena, said: "This is an utterly new
phenomenon to us, and we are still in the process of understanding the physics
involved."
Racing through space
Mira (also called Mira A) has captivated astronomers for more than 400
years.
It sits about 350 light-years from Earth in a constellation known as Cetus, and
is accompanied in orbit by a smaller secondary star, called Mira B, forming a
binary system.
Billions of years ago, Mira would have been much like our Sun, but as it now
enters its death-throes it has swollen into a type of star known as a red
giant.
As it races through space at 130km/s (80 miles per second) it sheds vast
amounts of material.