Using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST), scientists from the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) and its collaborators domestically and internationally have found a binary pulsar with a 53-minute orbital period.
The discovery of this binary system named PSR J1953+1844 or M71E fills the gap in the evolution of spider pulsar systems. The findings were published in Nature on June 20, 2023.
The first pulsar was discovered in 1967. There have so far been discovered roughly 3,000 of these amazing objects, which rotate steadily and fast like spinning tops in the sky.
Some pulsars are found in binary systems, where they orbit alongside other stars. The pulsar will consume matter from the companion star if the two stars are near to one another. The companion star is heavy at first. However, when the pulsar “eats” its companion star, the two stars are forced to orbit one another more closely and faster.
In contrast, the pulsar is unable to continue plundering as the star loses mass and becomes lighter, which causes it to push the companion star away. As a result, the pulsar’s orbital speed slows down.
The orbital of the binary is almost face-on such a system is extremely rare. FAST found it in the vast sea of stars using its extremely high detection capabilities. This filled the gap in the evolution of spider pulsar systems and reflects FAST’s unprecedented sensitivity.
Jiang Peng
Astronomers named the objects in these two stages after the redback and black widow spiders, respectively, because of this behavior, which is similar to female spiders consuming male spiders. They are collectively known as spider pulsars.
It can take hundreds of millions of years for a redback to evolve into a black widow. Only binary pulsar systems in the redback and black widow states have previously been discovered; no intermediate states had yet been identified.
The rationale is that this hypothesis predicts an intermediate pulsar with an extremely short orbital period and a very tight distance between the two stars, making detection difficult. Because of this, the notion that spider pulsar systems evolved from redback to black widow has not been completely disproved.
Now, however, the possibility of this evolutionary path has been confirmed by FAST, the world’s largest and most sensitive radio telescope. The study team employed long-term observation by FAST to find the lowest orbital period yet discovered 53 minutes in a spider pulsar system.
The researchers concluded that the system was in an intermediate condition on the evolutionary road from redback to black widow based on a variety of indications during observation, thus completing the gap in the theory of spider pulsar evolution.
“The orbital of the binary is almost face-on such a system is extremely rare. FAST found it in the vast sea of stars using its extremely high detection capabilities. This filled the gap in the evolution of spider pulsar systems and reflects FAST’s unprecedented sensitivity,” said Jiang Peng of NAOC, co-corresponding author of the study.
Nature reviewers described the result as a “very interesting pulsar binary system. This discovery shortens the record for the shortest orbital period of a pulsar binary system by about 30%, indicating a new and unknown process in the evolution of spider pulsars.”
