BEIJING, April 22 (Xinhua) -- They are stellar systems of two or more stars bound by gravity and too tight-knit to be "seen" by any telescope, yet their light reveals hidden clues, and Chinese astronomers have now uncovered more than 20,000 such "invisible" systems that had never been recorded before.
Using medium-resolution spectral data from China's Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), also known as Guo Shoujing Telescope, which is named after the renowned 13th-century Chinese astronomer and hydraulic engineer, researchers have identified more than 20,000 spectroscopic multiple-star systems, providing a valuable new sample for understanding how stars form and evolve, Science and Technology Daily reported on Wednesday.
The study not only significantly enriches the known catalog of multiple-star systems but also provides an efficient and reliable new method for future searches, said Li Kai, a professor at Shandong University in east China and the corresponding author of the study.
"As data continues to accumulate, our understanding of the stellar universe will deepen," said Li.
Spectroscopic multiple-star systems are stellar families, in which member stars are so close to each other and so far away from Earth that even the most powerful telescopes can not resolve them visually. Their existence can only be confirmed by analyzing the light they emit, or spectra.
These systems are extremely common in the Milky Way and play a key role in stellar birth, evolution and gravitational interactions. "However, compared with the vast number of stars in our galaxy, the number of such systems humans have confirmed remains pitifully small," Li said.
To hunt them down, the research team employed a specialized program to analyze LAMOST spectra. After training the algorithm on carefully selected samples to ensure accuracy, the astronomers applied it to nearly 450,000 celestial targets.
The result is fruitful with 15,887 binary-star candidates, 8,771 triple-star candidates, and an additional 294 "hidden" binary systems.
The vast majority of stars in these systems -- between 87 and 97 percent -- are main-sequence stars, ordinary stars like the Sun that are in stable burning phases, the analysis shows.
The team also conducted orbital analysis on systems with sufficient observational data, successfully deriving orbital parameters for more than 300 binary systems, and identifying orbital information for over 40 hierarchical triple-star systems, where the stars have a ranking structure.
For hierarchical triple-star systems, typically, two stars are relatively close to each other, orbiting around a common center, while the third star orbits this pair from a further distance.
The findings have been published in The Astrophysical Journal Supplement Series (ApJS), a leading international astronomy journal.
The LAMOST telescope, located in Xinglong County in north China's Hebei Province, is a national major scientific facility operated by the National Astronomical Observatories under the Chinese Academy of Sciences.
With an effective aperture of about four meters and 4,000 optical fibers, it has one of the highest spectral acquisition rates of the astronomical telescopes in the world. ■
