An intriguing spiral structure surrounding a pulsing red giant star may be offering a preview of how the sun will behave at the end of its life.
Using the Atacama Large Millimeter/Submillimeter Array (ALMA) in northern Chile, an international team of astronomers found the spiral structure, one never seen before, in the envelope of gas and dust around a red giant about 1,000 light-years from Earth and took a detailed three-dimensional reading of its composition.
The spiral is thought to be created from the gases being expelled by thedying red giant called R Sculptoris. The structure provides information about the velocity of the wind blowing off of R Sculptoris, revealing that the star has expelled three times as much mass as previously estimated. "We can 'walk along' the spiral and use it as a clock to see what happened when," said Matthias Maercker, of Germany's University of Bonn. [Weird Spiral Around Red Giant Star (Video)]
Low- to intermediate-mass stars like the sun expand into red giants during the last stages of their evolution. When the sun reaches this stage in about 5 billion years, its outer layer will spread as far as Earth's orbit.
Every 10,000 to 50,000 years, these gaseous behemoths burn helium for a few hundred years in a runaway process known as a thermal pulse, causing the layers of the star to mix.
Thermal elements are an essential part of late stellar evolution and take time to reach the outer layers of the star. By studying the corkscrewed expulsion from R Sculptoris, the astronomers calculated that the star was shedding more mass during thermal pulses than had been estimated.
"This means that much more mass is lost during a time where new elements cannot yet be incorporated into the wind," Maercker said. "Hence it will take longer for these elements to be blown into space ― most likely, only during the next pulse."