Photo released on July 7, 2022 shows a professional rendering of a binary star system in Beijing. (Photos：China News Service)

A joint research team of Chinese and Australian astronomers has detected a binary star system ejecting a common envelope, a key process of the binary star evolution, which could be of great importance to studies of the expansion of the universe and dark energy.

The two stars get closer and spin with each other faster and faster. About 10,000 years ago, they ejected their common envelope, made up of gas, which is expanding and leaving the binary system at a speed of 200 km per second.

The research was published online on the Monthly Notices of the Royal Astronomical Society on Thursday.

Li Jiangdan, first author of the research finding, introduces the evidence for the direct discovery in Beijing, July 7, 2022.

Han Zhanwen, corresponding author of the research finding, introduces the evidence for the direct discovery in Beijing, July 7, 2022.