Researchers describe oxygens different shapes 17 hours ago by Tracey Peake This image shows the nuclear shape of the ground and first excited state of oxygen-16. Credit: Dean Lee, NC State University (Phys.org) —Oxygen-16, one of the key elements of life on earth, is produced by a series of reactions inside of red giant stars. Now a team of physicists, including one from North Carolina State University, has revealed how the elements nuclear shape changes depending on its state, even though other attributes such as spin and parity dont appear to differ. Their findings may shed light on how oxygen is produced. Carbon and oxygen are formed when helium burns inside of red giant stars. Carbon-12 forms when three helium-4 nuclei combine in a very specific way (called the triple alpha process), and oxygen-16 is the combination of a carbon-12 and another helium-4 nucleus. Although physicists knew what oxygen-16 was made of, they were still puzzled by the fact that both the ground and first excited states of the element had zero spin and positive parity. A similar situation occurs in carbon-12 with the ground state and second zero-spin state known as the Hoyle state. At room temperature, only the ground state of oxygen-16 is seen due to the very cold temperature compared to nuclear energies. But the excited states of oxygen-16 become important for the helium-burning reactions inside stars. Its expected that oxygen-16 would have zero spin and positive parity as its ground state, says NC State physicist Dean Lee, team member and co-author of a paper describing the research. What is unexpected is that the first excited state also has these qualities. It made us wonder what the real difference is between the states, which required looking at the structure of the eight protons an
Posted on: Fri, 14 Mar 2014 09:40:37 +0000
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