Physics scientists have measured the first-ever direct measurement of one of the most powerful elements in the Universe, as exploding stars.
A team of physicists led by Gavin Lotay, University of Surrey, UK, observed the proton capture process that is thought to be occurring in core-collapse supernovae.
Scientists now know how it happens in detail. The measurements allow us to better understand the production of the mysterious isotopes called "p-nuclei".
Stars can be viewed as the basic factories of the Universe. Before stars were created and began to smash together nuclei within their cores, the Universe consisted mainly of hydrogen and helium. The cosmos was infused with heavier elements through stellar nuclear fusion, including carbon and iron for the largest stars.
Here is where core-fusion runs into trouble. Core fusion is a process that produces more heat and energy than it uses to make iron. This causes the core temperature to drop which results in the star's death in a stunning kaboom called the supernova.
Here, physicists believe that even more heavy elements are created. Because the explosion is so energetic, atoms can collide with force to capture each other's components. The explosion doesn't necessarily have to be supernova. Heavy elements can form in collisions between two neutron star. However, the principle is the exact same. A cosmic splodo boom with enough energy to forge elements = colossal.
Then, there are the P-nuclei. These 30 naturally occurring heavy elements are around 1% of all the elements in our Solar System. Their formation is still a mystery.
Isotopes can be forms of the same element which vary in atomic mass. This is usually due to a different number of neutrons within the nucleus while the number protons remains the same. P-nuclei, although neutron-deficient and proton-rich, are rare isotopes. This makes it difficult to determine how they were forged.
Gamma is currently the most popular model. It involves atoms capturing protons in an energetic event. This would make a chemical element a number of protons. It would then transform it into another element in the periodic table. The result is a neutron-poor Iotope.
These observations were made using the Isotope Separator and Accelerator II at TRIUMF National Laboratory in Canada, which produced a beam of radioactive rubidium-83 atoms. To record and observe the process taking place in the beam, the TRIUMF–ISAC Gammaray Escape Suppressed Spectrometer (EMA) and Electromagnetic mass spectrometer (EMS) were used.
Researchers concluded that the results indicated the production of p-nucleus strontium 84. This is consistent with the gamma procedure. The thermonuclear reaction rate, which was predicted to be lower in theoretical models, resulted in higher strontium-84 production.
The researchers stated that their recalculated production rate was consistent in strontium-84 abundances seen in meteorites and could shed light on other astrophysical processes.
Lotay stated that the coupling of a high resolution gamma-ray array and an advanced electrostatic separator in order to measure gamma processes reactions is a significant milestone in direct measurement of astrophysical phenomena.
"It was widely believed that such measurements were beyond the reach of current experimental technology, but the new study has opened up a wealth for the future."
The research was published in Physical Review Letters.
