Chinese scientists have revealed the origin of calcium in first stars by using the world's deepest underground laboratory in China's Sichuan Province.

According to a study published online in the journal Nature, Chinese researchers in relevant experiments in the laboratory successfully verified the hypothesis that calcium comes from a key breakout reaction of carbon, nitrogen and oxygen cycle (CNO cycle), revealing the origin of calcium in the star.

He Jianjun of Beijing Normal University, the first corresponding author of the article said the CJPL can greatly reduce the influence of cosmic rays and provide unique conditions for direct measurement of important nuclear reactions of astrophysical interest.