China News Agency, Beijing, March 27th (Reporter Sun Zifa) The reporter learned from the National Astronomical Observatory of the Chinese Academy of Sciences on the 27th that after nearly two years of observational research, astronomers have passed the 500-meter spherical spherical radio telescope (FAST), commonly known as the "sky eye" A pulsar binary system was found in the Wuxian globular cluster (M13), and the pulsar timing observation confirmed that the binary system consists of a pulsar and a white dwarf.
This is the first pulsar double star system discovered by FAST, and it is also the first time that FAST has released the results of a pulsar timing observation study. This important astronomical observation research was completed by Wang Lin, Ph.D. student of the National Astronomical Observatory of the Chinese Academy of Sciences, and Bloomberg researcher in collaboration with Professor Benjamin W. Stappers of the University of Manchester. ApJ).
According to the National Astronomical Observatory of the Chinese Academy of Sciences, from December 2017 to September 2019, Wang Lin and other researchers have used the FAST ultra-wideband receiver to observe once and the multi-beam receiver to observe 24 times. The cumulative time is about 31 hours. A millisecond pulsar M13F in a binary star system was found in M13, and another pulsar M13E in the cluster was identified as an eclipse binary star. The orbit ellipticity of the four pulsar binary star systems including M13F was also measured for the first time in M13 At the same time, the world's best timing results for M13's existing pulsars were obtained. This is FAST's first high-sensitivity pulsar search and timing observations for globular clusters. It not only shows FAST's ability to detect faint pulsars, but also fills a blank in the study of the properties and distribution of pulsars in globular cluster M13.
Researchers said that the pulsar M13F has two characteristics: first it is a millisecond pulsar with a rotation period of 3 milliseconds, and it is also the second fastest pulsar in M13; second, it is in a dual star system and has a mass White dwarfs with a lower limit of about 0.13 times the mass of the sun revolve around each other to form a binary star system with a revolution period of 1.4 days. These two characteristics are largely due to the unique environment of globular clusters. In the future, FAST will need to continue to make long-term observations of M13 to reveal the evolution of pulsars in low-density globular clusters.
The discovery of the first pulsar binary system this time proves that FAST not only has the ability to find unknown pulsar binary stars, but also makes better observations than other telescopes. The research team will continue to use FAST to do more research on globular cluster pulsars in the future, and most look forward to discovering more extreme binary systems such as pulsars-black hole binary stars that have not yet been discovered.
The globular star cluster is composed of a large number of stars bound by gravity, most of which are in the silver halo, and are considered to be radio pulsars, especially millisecond pulsars “production plants”. At present, astronomers have found 157 pulsars in about 30 globular clusters, more than 90% of which are millisecond pulsars, and nearly 60% are in binary star systems. This proportion is much higher than pulsars in silver disks. FAST's discovery of M13F pulsars this time is expected to further enrich the globular cluster pulsar samples and promote the study of dense celestial body evolution.
In January 2020, FAST successfully passed the national inspection and put into operation. Up to now, 114 pulsars known as "cosmic lighthouses" have been discovered and certified. At the same time, FAST is launching scientific observation projects such as pulsar timing arrays, drift-scanning multi-scientific target surveys, and entering the scientific output stage. (Finish)