MATHEMATICAL SCIENCES

Tsinghua’s team discovered a rare binary star system


Recently, an international team led by Professor Zhu Wei of the Department of Astronomy of Tsinghua University discovered two rare star systems, and the results were published online in the Astrophysical Journal Express.

It is reported that the binary star system refers to a celestial system composed of two stars that appear to be very close to each other relative to other stars. Because binary stars and their protoplanetary disks are condensed from the same giant rotating nebula, the disks are usually in the same plane as the stars’ orbits — just as the orbits of most planets and moons in the solar system are in the same plane.

However, there is another rare binary system in the universe, in which the disk of gas surrounding the binary star is at an angle to the orbital plane of the star. Because of this tilt, the protoplanetary disk oscillates like a gyroscope, a movement called “precession.” When they “precede,” protoplanetary disks move between us and the star, in units of decades, causing the light of the central star to dim. The total brightness of a binary star changes periodically, producing a unique light curve. Zhu Wei’s team discovered such binary star systems, which were named Bernhard-1 and Bernhard-2, respectively.

Renderings of the double star system produced by the scientific research team Courtesy of Tsinghua University

The team observed that Bernhard-1 was dimmed for 112 out of every 192 days, while Bernhard-2 was in a dimming state for 20 days every 62 days. Viewed from Earth, these dimmed states indicate that one star in each binary is moving behind the disk. When the star reappears, the brightness of the system returns to normal.

Zhu Wei said that the two binary star systems are 3,000 light-years away from Earth to 10,000 light-years, and enthusiasts with 20-centimeter or more aperture telescopes can see the process of their brightness change, but unfortunately, existing telescopes are not yet able to distinguish between binary stars and protoplanetary disks.

“The discovery of this rare and peculiar system is important for our understanding of planet formation.” Zhu Wei said that since the protoplanetary disk is the birthplace of the planet, the emergence of the binary star system will help researchers to study the problem of non-coplanar structure objects and the planetary systems they produce in greater depth, “We also believe that there will be more discoveries of such rare objects in the near future.” ”

Zhu Wei led the team to include two European amateur astronomers and researchers from the California Institute of Technology, the Purple Mountain Observatory, the University of Toronto and Peking University, and Zang Weicheng, a 2017 doctoral student in the Department of Astronomy of Tsinghua University, and Gan Tianjun, a 2018 doctoral student. (Source: China Science Daily Chen Bin)

Links to related papers:https://doi.org/10.3847/2041-8213/ac7b2d



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