Team Led by China Discovers Unique Binary Gravitational Wave Source

A remarkable binary star system, composed of a hot subdwarf and a white dwarf, was recently discovered by scientists, who noted the pair orbit each other at an unprecedented speed.

The speedy pair of stars are predicted to produce robust gravitational wave radiation within the milli-Hertz frequency range. This radiation is anticipated to be measurable by future observatories focusing on gravitational waves in space.

The groundbreaking discovery, made by Professor Wang Xiaofeng's team at Tsinghua University along with additional collaborators, utilized the Tsinghua University-Ma Huateng Telescope for Survey (TMTS). The TMTS, located at the National Astronomical Observatories' Xinglong Observatory in Hebei Province, in the north of China, contributed greatly to this discovery. The findings were recently published in Nature Astronomy.

The team's research led to the detection of a peculiar binary system with an orbital period of just 20.5 minutes, known as TMTS J0526. Situated approximately 2,760 light years away from Earth, this system contains a carbon-oxygen white dwarf star and a low-mass subdwarf B star, which possesses only 0.33 solar mass.

The hot subdwarf of the TMTS J0526 system boasts a radius merely seven times that of Earth, marking it as the smallest known star in terms of volume, stated Lin Jie, a significant contributor to the research team.

Wang Xiaofeng posits that this discovery is an essential source for future gravitational wave detection in space. "It supports Han Zhanwen and his team at the Yunnan Observatory's 2003 theoretic proposition of the formation of this unique binary system," asserted Wang Xiaofeng, referencing the academician of the Chinese Academy of Sciences.

"The breakthrough can enhance our comprehension of star evolution theory, which forms the foundation of our understanding of the universe's evolution," he further elaborated.

The TMTS, a specially designed multi-telescope optical survey instrument, was established by Wang Xiaofeng's team, with the support of the Ma Huateng Foundation and Tsinghua University.

Since its commissioning in 2020, the TMTS has been executing a continuous scan of the northern celestial hemisphere with an approximate one-minute cadence.

By the end of 2023, TMTS will have compiled photometric data of more than 27 million stars, encompassing dozens of valuable short-period variable sources. Of these, TMTS J0526 is notable for having one of the shortest periods.