Astronomers using a powerful telescope have discovered a totally unexpected spiral shell of cosmic dust and gas surrounding a red giant star.
This is the first time scientists have found a full three-dimensional information about such a spiral structure, along with an outer spherical shell, around the old star R Sculptoris.
The strange shape was probably created by a hidden companion star orbiting the red giant.
A team using the Atacama Large Millimeter/submillimeter Array (ALMA) were surprised to find that far more material than expected had been ejected by the red giant.
There is probably a previously unseen companion star orbiting the star, researchers said.
“We’ve seen shells around this kind of star before, but this is the first time we’ve ever seen a spiral of material coming out from a star, together with a surrounding shell,” says the lead author Matthias Maercker ESO and Argelander Institute for Astronomy, University of Bonn, Germany.
Because they blow out large amounts of material, red giants like R Sculptoris are major contributors to the dust and gas that provide the bulk of the raw materials for the formation of future generations of stars, planetary systems and subsequently for life.
“When we observed the star with ALMA, not even half its antennas were in place. It’s really exciting to imagine what the full ALMA array will be able to do once it’s completed in 2013,” said Wouter Vlemmings from Chalmers University of Technology, Sweden, a co-author of the study.
A thermal pulse leads to material being blown off the surface of the star at a much higher rate, resulting in the formation of a large shell of dust and gas around the star.
After the pulse the rate at which the star loses mass falls again to its normal value.
Thermal pulses occur approximately every 10, 000 to 50,000 years, and last only a few hundred years.
The new observations of R Sculptoris show that it suffered a thermal pulse event about 1,800 years ago that lasted for about 200 years. The companion star shaped the wind from R Sculptoris into a spiral structure.
“By taking advantage of the power of ALMA to see fine details, we can understand much better what happens to the star before, during and after the thermal pulse, by studying how the shell and the spiral structure are shaped.
“In the near future, observations of stars like R Sculptoris with ALMA will help us to understand how the elements we are made up of reached places like Earth. They also give us a hint of what our own star’s far future might be like,” said Maercker in a ESO statament.
The study findings have been published in the journal Nature .