The story has rather a commonplace beginning. British radio astronomer Antony Hewish – who was already well-known in the 1960s – asked his postgraduate Jocelyn Bell to make her own telescope to explore the sky and search for new quasars. With the help of her colleagues she coiled kilometers of wire around hundreds of wooden poles. Thus, she created a very sensitive aerial that subsequently began to receive strange signals on a regular basis.
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At first Jocelyn thought that this was a form of interference from a military or commercial station located nearby. Afterwards, she started checking engineering data of her wire entanglements. In the end Jocelyn concluded that signals were of space origin.
Her advisor and she were even frightened at first when they thought about green aliens who sent them a coded message from the depth of space. For half a year they kept Bell’s discovery dark until they published a joint report on pulsatile signals in Nature magazine in 1968.
The article was a real bombshell. The whole world spoke of objects named pulsars overnight. Theorists rapidly found that it was a matter of evolution of small stars whose helium core had burnt down and the rest of the mass collapsed on itself under the influence of gravitation. As a result, electrons were implanted into protons with neutron formation. This is the way neutron stars appear, the mass of which amounts to 1,030 tons, whereas their diameter may equal 20 kilometers. Speaking about the density of such objects, Bell made the following comparison: “Think of the whole mankind packed in a small thimble.”
Monstrous energy that is literally concentrated in a point of space urges a neutron star to make several revolutions per second. For pulsars revolve at an equal speed, they are one of the most regular clocks. The discovery of pulsars enabled scientists to perform experiments to verify Einstein’s relativity. Now they contrived to confirm the general theory of relativity accurate within 0.05 percent.
As time passed, it became clear that pulsars are just extinct remnants of relatively small stars with various masses. If a newborn star mass does not exceed one hundred solar masses and the helium content equals 2-40 solar masses, than its evolution will lead to formation of a small pulsar with a black hole in its center. It may end up in a subdued outburst of a supernova.
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