Stars are a key to our understanding of the universe. Unlike our nearest star, the Sun, most stars in the sky have their own companions that accompany them through the evolutionary process.
On July 7, the Royal Astronomical Society Monthly (MNRAS) published a scientific discovery jointly completed by Chinese and Australian scientists online. The team led by Han Zhanwen, an academician of the Chinese Academy of Sciences and a researcher at the Yunnan Astronomical Observatory of the Chinese Academy of Sciences, and a team of starmappers led by Chris Wolf of the Australian National University, found for the first time direct evidence of the existence of “co-cladding” in binary stars.
Artistic drawing of the achievement (courtesy of Beijing Planetarium, painted by Yu Jingchuan)
Zhao Gang, a researcher at the National Astronomical Observatory, commented: “This original work has opened up a new research direction that will make it possible to study the formation and evolution of dense binary stars in the near future and to restore their early physical properties and states.” ”
The evolution of binary stars will change the existing evolutionary fate of stars, and in the subsequent “star life”, binary stars will form double black holes, binary neutron stars and other celestial bodies that occupy an important position in modern astronomical research. As early as 1976, the Polish-American scientist B. Pakszynski Paczynski proposed a theory predicting that there is an evolutionary process of “co-cladding” in binary stars, which will profoundly affect the fate of binary stars. However, for nearly half a century, no scientist has actually observed the existence of a shared cladding.
Han Zhanwen explained: “One star in a binary star expands violently due to material loss, enveloping the other star in an outer layer, forming a common envelope. At this point, the entire binary star system looks like a double yolk egg, with the two yolks being the stars themselves and the egg whites having a common envelope. ”
In order to find evidence of the real existence of the co-cladding, Chinese and Australian scientists have discovered a Hota dwarf binary star J1920 23,000 light-years away in the southern hemisphere through the Australian National University’s 2.3-meter wide-field telescope and kepler satellite.
Li Jiangdan, the first author of the paper and a doctor of the Yunnan Astronomical Observatory, introduced that the researchers used the observation data to conduct photometric and spectral observations successively, and obtained the relevant parameters of this binary star. The analysis found that the two stars are getting closer and closer, with an expanding shell around them, leaving the binary at a speed of about 200 kilometers per second.
“A series of analyses not only use many existing sky survey data, but also put forward their own spectral observation needs, sequentially progressive, logically coherent, interlocking.” Zhao Gang said, “This process fully reflects the scientific thinking of astronomers. ”
Commenting on the achievement, Brian Schmidt, president of the Australian National University and winner of the 2011 Nobel Prize in Physics, said: “This major discovery opens up new avenues for a deeper understanding of the evolution of shared cladding. I sincerely wish that the future of Chinese astronomy will be better and better, and maintain fruitful international cooperation. ”
Scientists look forward to using the existing low-resolution spectral data of the Guo Shoujing Telescope (LAMOST), the ongoing time-domain medium-resolution spectral observations, and China’s large-aperture astronomical optical telescope that has not yet been approved to jointly contribute to solving more star mysteries. (Source: China Science Daily Gan Xiao)
Related paper information:https://doi.org/10.1093/mnras/stac1768