95% are the latest discoveries! Guo Shoujing telescope made new achievements

Using the medium-resolution spectral data from the Guo Shoujing Telescope (LAMOST), researchers from units such as the National Astronomical Observatory found 3133 spectral binary stars and 132 spectral three stars and accurately measured their viewing speeds, 95% of which are newly discovered multi-star systems. The relevant research results were published online in the internationally renowned astronomical journal "Supplement to the Astrophysics Journal".

"This is the largest multi-star table with time-domain spectral information to date, providing a resource of scientific heritage value for conducting related research." On November 11, Shi Jianrong, a researcher at the National Astronomical Observatory of the Chinese Academy of Sciences, told the Science and Technology Daily reporter.

About half of the stars in the Milky Way are in binary systems. Through photometric and spectral observations, researchers can obtain accurate orbital parameters, star mass, and radius of binary stars. "The possible transfer of material in binary systems also makes their evolution extremely complex. Binary stars are important members of the study of the formation and evolution of stars and even the Milky Way. Shi Jianrong said.

Traditionally, one of the main means of discovering binary star systems is masking, just as a solar eclipse is due to the sun being obscured by the moon, two child stars in a binary system also obscure each other as they orbit each other. "However, due to the inclination of the orbit of the binary star, the larger the inclination, the more difficult it is to cover up, so many binary star systems cannot be observed using metering." Shi Jianrong said that spectral observations can recognize these binary star evidence that have not been masked.

More importantly, spectroscopic observations can provide information such as the orbital parameters of binary stars and the parameters of the star's atmosphere, which, combined with the metering data, can determine other important information such as the mass, radius, and luminosity of the star. In addition, there are some special binary star systems in which there is an "invisible" substar whose mass can be found and inferred through spectral observations.

If the "invisible" child star is a white dwarf, it is possible that it will eventually evolve into a supernova; if the child star is massive enough, it may even be a black hole. "Therefore, with the continuous accumulation of data from large-scale spectral sky survey projects such as LAMOST, the study of dense sub-stars in binary star systems through spectroscopic methods has also become a research hotspot in recent years." Yan Hongliang, a researcher at the Nebula Program of the National Astronomical Observatories of the Chinese Academy of Sciences, said.

Using the method of cross-correlation function, the researchers measured the apparent velocity of the medium-resolution spectrum of LAMOST DR7, finding a spectrum with two or three apparent velocity components. In the end, more than 3,000 spectral binary and three-star systems were identified, and the value of the visual speed of each sub-star at different observation moments was given.

Li Chunqian, the first author of the paper and a doctoral student at the National Astronomical Observatory of the Chinese Academy of Sciences, said that thanks to the LAMOST time domain sky survey project, more than 2,500 targets in these identified multi-star systems contain data from multiple observations, of which 525 spectral binary stars and 31 three-star stars have been observed at least 6 times. Therefore, the largest multi-star table with time-domain spectral information published to date based on LAMOST data provides key data support for further research into issues such as the proportion and nature of binary stars. At the same time, it also demonstrates the power of lamost medium-resolution spectral surveys in spectroscopic multi-star research.

Presumably, the research team expects to find about 1500 new spectral multi-star systems per year in LAMOST's medium-resolution spectral data. "As LAMOST medium-resolution spectral observations unfold, more and more multi-star systems with time-domain spectral information will be discovered." Li Chunqian said.

Wen/Science and Technology Daily reporter Lu Chengkuan

Editor/Fan Hui