Recently, Chinese scientists announced the use of China’s 500-meter spherical radio telescope (FAST; commonly known as the “Sky Eye” telescope) in the Constellation of Wuxian globular cluster (M13) found a pulsar binary star. The paper will be published soon in the Astrophysical Journal, a well-known international astronomical journal.
Screenshot from https://arxiv.org/abs/2002.05938
This is the first pulsar binary found by FAST.
The pulsar also has three key words: pulsar binary, millisecond pulsar, and globular cluster pulsar.
It’s a “pulsar binary.”
Astronomy refers to two close stars as “double stars”.
Here is “close to” there are two layers of meaning, the first is just to appear very close, when in fact the space between the two is far away, there is no physical connection, called “optical binary”;
In the field of pulsars, when it comes to binary stars, they refer to physical binary stars. The pulsar-related binary system is divided into two categories: if only one of the binary stars is a pulsar, it is called a pulsar, and if both stars of the binary system are pulsars, it is called a “double pulsar”.
Motion: Pulsating Binary
FAST this time found a pulsar in a binary system. After many observations of the pulsar, astronomers have estimated that the other star with the pulsar should be a white dwarf about 0.16 times the mass of the sun.
It’s also a millisecond pulsar.
FAST’s discovery of the pulsar is also a millisecond pulsar.
As early as 2018, when FAST found a millisecond pulsar in a gamma-ray source, we described the classification of pulsars in some detail and what constitutes a millisecond pulsar. Simply put, a millisecond pulsar is a class of pulsars with a faster rotation speed and a more stable rotation speed.
The currently accepted theory of the birth and evolution of millisecond pulsars is that millisecond pulsars are formed in a process similar to jumping “waltz”: two stars in a binary system, fat (i.e., the main star) will first experience a supernova explosion, throwing part of its own material, if it is a “dance partner” (i.e., companion) is relatively thin and will be kicked out quickly, while the binary system collapses, while the main star explodes and leaves a portion to collapse into a fast-rotating neutron star; if the companion star’s “weight” is enough to withstand the impact of a supernova explosion, it will remain in the previous binary system, with the newly formed neutron star continuing this “waltz” Until the end of life.
If the radiation beam of the north-south magnetic pole of the neutron star can sweep across the Earth with its rotation, it is what we call pulsar.
Motion Picture: Pulse Dares Stars Online Flash
A pulsar in a binary system can accelerate its rotation by absorbing the material of the companion star and become a millisecond pulsar.
Neutron Star-White Dwarf and Double Neutron Binary System Evolution Model http://www.jb.man.ac.uk/distance/frontiers/pulsars/lorimer-review.pdf
It is important to note that if there is only one pulsar in a dual neutron star system, the system is also a pulsar, not a binary.
It’s not over, it’s a spherical cluster pulsar.
FAST’s discovery came as astronomers deliberately searched for pulsars in globular clusters. A pulsar in a globular cluster is a globular cluster pulsar.
Why look for pulsars in globular clusters? It’s about what a globular cluster is.
As the name suggests, a globular cluster is a globular cluster. They usually look like this:
Wuxian Globinto (M13)
This is the image seen by the telescope. With the naked eye, these dense stars gather within a sky smaller than the full moon.
Many stars are bound together by powerful gravity, “squeezed” in a spherical space, and the closer they get to the center, the higher the density, which is the globular cluster. The density of stars in globular clusters is 100 to 1,000 times that of the stars in the Milky Way around us. Currently, there are more than 150 globular clusters found in the Milky Way, of which about 30 can be seen by FAST.
The dense stellar environment of globular clusters creates very favourable conditions for pulsars to find and exchange “dance partners” and is therefore more likely to produce binary or even multi-star systems.
Astronomers have many questions to understand about, such as:
How fast will the “waltz” of such a segment accelerate the pulsar’s rotation?
What kind of “dance partner” will they find?
Will there be pulsars who come to several “dance partners” to dance in circles?
Current observations also provide strong evidence for astronomers’ guesses.
Here are some interesting pulsars that astronomers have found in globular clusters:
1) In 1991 Prince discovered a double neutron star system in the globular cluster M15.
2) In 1999 Thorsett et al. discovered a three-star system in the globular cluster M4, a pulsar PSR B1620-26, a white dwarf star and a companion with a mass close to Jupiter.
3) In 2006, Dutchman Hessels discovered psrorist PSR J1748-2446ad, the fastest spin, in the globular cluster Terzan 5, turning 716 revolutions per second.
4) In 2008 Freire et al. found the largest pulsar, PSR B1516,02b, the largest mass of the glob m5.
What’s the use of finding these “special” pulsars?
Astronomers predict that neutron stars will turn at about 700 revolutions per second. The fastest pulsar known to be at the fastest speed, turns 716 revolutions per second, in line with theoretical predictions.
But if we find a fast-moving pulsar, such as a fast-moving pulsar, turning more than 1,000 or even 2,000 revolutions per second, it challenges our understanding of neutron stars now, is it wrong, or is it that the pulsar is no longer a neutron star, but a quark star, a quark group star, or something strange?
The answers to these questions are unknown until such pulsars are actually discovered.
But the only certainty is that if pulsars are found at much faster than expected, our understanding of the physical state of neutron stars will be rewritten. This will be a landmark discovery.
And if we’re lucky enough to see a pulsar captured by a star-level black hole in the “swap partner” activity, it will be an ideal laboratory for testing the natural nature of gravity theory. This may provide another powerful support for Einstein’s general theory of relativity.
Studying globular pulsars will help answer our questions about the globular clusterite itself.
Pulsars in the powerful gravitational pull of globular clusters could be a useful tool for direct study of the gravitational distribution of globular clusters, promising to confirm the existence of medium-mass black holes in the center of globular clusters, and by measuring the self-eity of globular clusters to speculate on the star’s own self,’ thus obtaining the orbit of the globular cluster sedrifying in the gravitational pull of the Milky Way. In addition, globular pulsars can explain the ionizing gas in the cluster, the distribution of magnetic fields, and the way stars interact within the cluster.
On January 11, 2020, FAST was officially put on duty through the national acceptance. It is believed that fast in the future will help astronomers discover more interesting pulsars and further lift the mystery of the universe.