Another important achievement! China's Sky Eye discovers the pulsar binary system with the shortest orbital period to date

The Five-hundred-meter Aperture Spherical Radio Telescope (FAST), known as the "China Sky Eye", has once again achieved an important scientific research result - the discovery of the pulsar binary system with the shortest orbital period known to date, filling a missing link in the evolution model of spider-type pulsar systems.

The relevant research results were published online in the international academic journal Nature on the 21st.

Image source: National Astronomical Observatory of the Chinese Academy of Sciences official website

The research team of the National Astronomical Observatory of the Chinese Academy of Sciences said that astronomical observations have previously found that some pulsars are in binary star systems and revolve with other stars. According to existing astrophysical models: if the distance between two stars is very close, the pulsar will swallow up the matter of the star next to it and make itself revolve faster and faster. Because the initial mass of the star is large, as the pulsar eats up the star, the distance between the two stars gets closer and closer, and the speed of their revolving around each other becomes faster and faster; as the binary star system evolves, the mass of the star becomes smaller after being eaten up, and it is difficult for the pulsar to continue to accrete and push the star away, so the speed of their revolving around each other also slows down.

Left: The red arrow indicates the position of M71E, next to the globular cluster M71; Right: The average pulse profile and polarization position angle of M71E from FAST observation data. Amateurs are happy to provide pictures of M71 and nearby stars.

Image source: National Astronomical Observatory of the Chinese Academy of Sciences official website

Because this behavior is similar to that of female spiders devouring male spiders to feed themselves in nature, astronomers named this type of celestial body after the names of two spiders, "redback" and "black widow", collectively called spider pulsars.

The evolution of the pulsar-star system from a "redback" to a "black widow" can take hundreds of millions of years. Previously, the astronomical community had only detected systems in the "redback" and "black widow" states, but had not discovered the intermediate state between the two. The reason is that the orbital period of the pulsar 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 evolution theory of spider pulsars from the "redback" to the "black widow" system has not been fully confirmed and has always attracted much attention from the academic community.

Photo by Xinhua News Agency reporter Ou Dongqu

In this study, the research team of the National Astronomical Observatory of the Chinese Academy of Sciences, with the help of the ultra-high sensitivity and extremely strong detection capability of the "China Sky Eye", confirmed the evolutionary path from the "Redback" to the "Black Widow" system. The research team used the "China Sky Eye" to detect the M71E binary star system. After long-term observation, it was determined that the two stars in this system take only 53 minutes to orbit once, with a rotation period of 4.44 milliseconds. It is the spider pulsar system with the shortest orbital period discovered so far. It was also determined to be in the intermediate state of the evolution process from the "Redback" to the "Black Widow" system. It was named the "Huamei Kouzhu" pulsar, thus filling the missing link in the theory of spider pulsar evolution.

It is understood that since its completion and operation, the "China Sky Eye" has discovered more than 780 pulsars, making it the world's largest astronomical observation facility with the most pulsars. At the same time, the stage of "producing good and great results" based on the discovery and research of the "China Sky Eye" has begun.

Comprehensive sources: National Astronomical Observatory of the Chinese Academy of Sciences, Xinhuanet, China News Network