Cosmic birth theory gets support
Researchers from Arizona State University and the Chinese Academy of Sciences studied a primitive meteorite from China known as the Ningqiang carbonaceous chondrite. This space relic formed shortly after the creation of the Solar System. The team found a rare isotope of sulphur - sulphur-36 - in the meteorite, which can be produced through the radioactive decay of a form of chlorine called chlorine-36. Because the sulphur isotope was found in an ancient mineral "inclusion" in the meteorite called sodalite, the researchers believe chlorine-36 could have been present in the early Solar System.
Chlorine-36 can form in two ways: by a supernova explosion, or by a nebular cloud being bombarded by radiation near the forming Sun. The researchers consider the latter explanation is unlikely since sodalite must have formed some distance away from our star. "There is no ancient live chlorine-36 in the Solar System now," said co-author Laurie Leshin, director of Arizona State's Center for Meteorite Studies. "But this is direct evidence that it was here in the early Solar System." Dr Leshin and others had previously found evidence for another radioactive isotope (or radionuclide) in the early Solar System called iron-60, which could also have been formed in a supernova. "It's producing a really strong argument that these radionuclides were produced in a supernova that exploded near the forming Solar System and seeded [it] with these isotopes," Dr Leshin added. If the controversial theory is supported by future work, it may have implications for understanding properties such as the size and shape of the Solar System, the physical make-up of the Earth and the chemistry that led to life.