The unique spiral in space spotted by the world’s most expensive ground telescope
A unique spiral structure encircling a dying star has been captured by scientists for the first time.
The spectacular picture is one of the first to come from the world’s most expensive ground-based telescope which produces images ten times sharper than Hubble.
It was built to study molecular clouds like the one around the red giant R Sculptoris which is 780 light years from Earth.
At 16,000ft up in the Chilean Andes the Atacama Large Millimeter/submillimeter Array (ALMA) is also the highest such machine on Earth.
The Atacama desert was chosen for its dryness and clarity.
The feature in the gas around the old star has never been seen before and is probably caused by a hidden companion star orbiting it.
The data reveals the shell around the star – which shows up as the outer circular ring – as well as a very clear spiral structure in the inner material.
The astronomers were also surprised to find far more matter than expected had been ejected by the red giant which is in the last phase of its life as is expanding as its temperature soars.
Professor Matthias Maercker, of Bonn University in Germany, 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.’
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.
The shot published in Nature is a glimpse of the potential of ALMA that will not even come into full operation until next year.
Study co-author Dr Wouter Vlemmings, of Chalmers University of Technology in Gothenburg, Sweden, said: ‘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.’
Late in their lives stars up to eight times bigger than the Sun become red giants and lose a large amount of their mass in a dense stellar wind..
During this stage they also periodically undergo thermal pulses – short-lived phases of explosive helium burning in a shell around the stellar core.
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 about every 10,000 to 50,000 years and last only a few hundred years.
The new observations of R Sculptoris show it suffered such an event roughly 1,800 years ago that lasted for about 200 years.
The companion star shaped the wind from R Sculptoris into a spiral structure.
Prof Maercker said: ‘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.
‘We always expected ALMA to provide us with a new view of the Universe but to be discovering unexpected new things already with one of the first sets of observations is truly exciting.’
The findings show how ALMA is already giving new insight into what’s happening in these stars and what might happen to the Sun a few billion years from now.
It operates at higher sensititivity and higher resolution than any previous ‘sub-millimetre’ radio telescope – and should allow us to see the formation of new solar systems.
ALMA can see through cold clouds of dust that ‘block the view’ of traditional infrared/visible light telescopes and as more antennae come online its images will get sharper.
It sits in the Chajnantor plateau 1500 km north of Santiago and is 4Oft tall.
Prof Maercker said: ‘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 the Earth.
‘They also give us a hint of what our own star’s far future might be like.’