Researchers from the National Astronomical Observatory of the Chinese Academy of Sciences (NAOC) and their domestic and international collaborators have discovered a pair of pulsars with an orbital period of 53 minutes using the 500-metre Aperture Spherical Radio Telescope (FAST). The discovery of this binary system, designated PSR J1953+1844 or M71E, fills a gap in the evolution of spider pulsar systems. Findings published Nature 20 June

The first pulsar was discovered in 1967. At present, about 3,000 of these fascinating objects have been found, which are spiraling regularly and rapidly in the sky.

Some pulsars exist in binary systems orbiting companion stars. If the two stars are close together, the pulsar will swallow material from the companion star to continue spinning. Initially, the companion star is heavy. But when a pulsar “eats” its companion star, the two stars converge and spin against each other at increasing speed. Conversely, as the star loses mass and becomes lighter, the pulsar cannot continue to strip it away, thus pushing the companion star away. As a result, the orbital velocity of the pulsar slows down.

This behavior, reminiscent of female spiders eating male spiders, inspired astronomers to refer to these two stages of objects as red and black widow spiders, respectively. Together they are known as spider pulsars.

Evolution from red ridge to black widow takes a long time, up to hundreds of millions of years. Previously, only binary pulsar systems in the red ridge and black widow states have been detected, and no intermediate states have yet been found. This is because the orbital period of the intermediate pulsar predicted by this theory is very short and the distance between the two stars is very close, creating observational problems. For this reason, the theory of evolution of spiders’ pulsar systems from red crosses to black widows has not been fully proven.

But the possibility of this evolutionary path has now been confirmed by FAST, the world’s largest and most sensitive radio telescope. Using FAST’s long-term observation, the research team discovered a spider pulsar system with the shortest rotation period ever discovered, at just 53 minutes. Based on various observations, the researchers determined that the system is in an intermediate state on the evolutionary path from red to black widow, thus filling a missing link in the theory of spider pulsar evolution.

“The binary system’s orbit is almost exactly the opposite – such a system is extremely rare. FAST used its extremely high sensing capabilities to find it in a vast sea of ​​stars. This filled a gap in the evolution of spider pulsar systems and [FAST’s ] “An unprecedented sensitivity,” said Jiang Peng of the NAOC, one of the study’s co-authors.

Nature critics have described the result as “a very interesting double pulsar system.” “This discovery marks a new and unknown process in the evolution of spider pulsars, reducing the record for the shortest rotation period of a binary pulsar system by about 30%.” Source