Important new discoveries!, Chinese Sky Eye Double Star | Team | Important
On June 21, 2023 (Beijing time), the international academic journal Nature published an important achievement of the scientific research team of the National Astronomical Observatory of the Chinese Academy of Sciences online. The team used the "Chinese Eye" FAST to discover a binary star called PSR J1953+1844, with an orbital period of only 53 minutes, which is currently the shortest pulsar binary system discovered. This discovery fills a missing link in the evolutionary model of spider like pulsar systems.
Searching and discovering radio pulsars is the core scientific objective of FAST. Pulsars are generated by stellar evolution and supernova explosions, named after the emission of periodic pulse signals, with a period between 1.4 milliseconds and 23 seconds. Short period pulsars, known as millisecond pulsars, can rival the best atomic clocks on Earth.
Astronomical observations have found that some pulsars are in binary systems, orbiting together with other stars. According to existing astrophysical models, if two stars are very close, a pulsar will swallow up the material of the nearby star and make itself rotate faster and faster. Due to the large initial mass of the star, as pulsars erode the star, the distance between the two stars becomes closer and their rotational speeds become faster; As binary star systems evolve, the mass of stars decreases after being heavily eroded, making it difficult for pulsars to continue accreting and pushing the stars away, resulting in a slower speed of their mutual rotation. Because this behavior is similar to the behavior of female spiders swallowing male spiders to feed themselves in nature, astronomers named these celestial bodies after two types of spiders, Red Back and Black Widow, collectively known as Spider Pulsars.
![Important new discoveries!, Chinese Sky Eye Double Star | Team | Important](https://a5qu.com/upload/images/984c7566b0f75c0fa1be13e107620ec3.jpg)
The evolution process from "Red Back" to "Black Widow" pulsar star systems can last for hundreds of millions of years. Previously, the astronomical community only detected systems in "red backed" and "black widow" states, but did not find any intermediate states in their evolution. The reason is that the orbital period of pulsars at this stage is very short, and the distance between the two stars is very close, which poses a great challenge to observation. Therefore, the theory of the evolution of spider like pulsars from a "red back" to a "black widow" system has not been fully confirmed.
Left: The red arrow indicates the position of M71E, next to which is the globular cluster M71.
Right: The average pulse profile and polarization position angle of M71E from the observation data of China's Tianyan.
![Important new discoveries!, Chinese Sky Eye Double Star | Team | Important](https://a5qu.com/upload/images/29a20fb6853a9bc4bcddcd73a95578c8.jpg)
With the ultra-high sensitivity and strong detection ability of the "Chinese Eye" FAST, this evolutionary path has been confirmed. The research team used FAST to detect the M71E binary star system, and after long-term observation, it was determined that the system's two stars only took 53 minutes to orbit once, making it the fastest spider pulsar system ever discovered. It has been determined to be in an intermediate state of the evolution process from red back to black widow system, filling the gap in the theory of spider pulsar evolution. At the same time, the orbital plane of the binary system is almost facing Earth and extremely rare, and further research is expected to yield more discoveries.
Shen Zhiqiang, Director and Researcher of the Shanghai Observatory of the Chinese Academy of Sciences, believes that the discovery of a pulsar with an orbital period of less than an hour and a rotation period of 4.44 milliseconds in the globular cluster M71 is rare. "This is a breakthrough in pulsar search and physical research, directly confirming the existence of the intermediate state pulsar binary predicted by the spider like pulsar theory. At the same time, it once again demonstrates the potential for significant scientific breakthroughs contained in FAST's ultra-high sensitivity advantage."
The reviewer of the journal Nature commented that this discovery shortened the record for the shortest orbital period of pulsar binary systems by about 30%, indicating the existence of new unknown processes in the evolution of spider like pulsars.
![Important new discoveries!, Chinese Sky Eye Double Star | Team | Important](https://a5qu.com/upload/images/10efc06553caaa27c9a628b6f9459576.gif)
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