Traces of supernova explosions found in annual tree rings
Exploding stars could have a greater impact on the Earth's climate than scientists believed. A new study has shown that traces of these cataclysms remain in the annual rings of trees.
Scientists at the University of Colorado have compiled a list of 18 supernova explosions that have occurred over the past 40,000 years. All of them occurred within a radius of 4900 light years from our planet. The authors then compared the estimated timing of the explosions with the bursts of carbon-14 remaining in the wood, according to the International Journal of Astrobiology.
Carbon-14 is a radioactive isotope of carbon. For its occurrence on Earth, an external influence is required, namely high-energy radiation from space. Scientists have previously found this substance in the annual rings of trees, but have associated it with solar flares.
New scientific work suggests a different explanation. It turned out that eight of the 18 supernova explosions occurred at about the same time as the short radiocarbon burst. This was especially evident in four cases. One of the explosions happened 13 thousand years ago, and its epicenter was located 815 light years from Earth. Shortly after this explosion, the level of radiocarbon in the atmosphere increased by about 3%.
Scientists noted that cosmic events could have a direct impact on life on Earth. Another study has shown that a supernova explosion may be associated with a mass extinction. It is also possible that these events changed the composition of the atmosphere and caused large-scale climatic changes – for example, global glaciation.
