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.
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.
The discovery of pulsars whipped up the development of cosmology that was acknowledged by physicists as hard science (by analogy with hard currency). It was 15 years ago that Russian scientist Vladimir Usov published in Nature his article in which he theoretically described the possible existence of millisecond pulsars (MSP), namely those spinning at over 700 rotations per minute. They were to possess gigantic magnetic fields and to be the most powerful source of gamma radiation, even more powerful than X-radiation.
At that time nobody could even imagine that in one and a half decade blazers or GRB (Gamma-Ray Bursts) will be really discovered in the depths of the Universe. This was one of the most remarkable discoveries of 2007.
The studying of pulsars is still under way thanks to new satellites, space platforms and earth-based telescopes. A recent issue of Nature magazine published an article by Sergei Blinnikov from Los Alamos National Laboratory where the US first atomic bomb was once created. His article highlighted the nature of the 2006 supernova outburst (SN2006gy – Super-Nova) that is at least ten times more powerful than a common star.
According to the scientist, the usual collapse of the core is not the only reason for outbursts. In massive stars the pressure of masses and gravitation set off the formation of pairs of electrons and their antiparticles – positrons, the so-called pair instability. They are so active that they start burning and explode. Energy of a star core is drastically decreasing, and after their collapse they explode once again with emission of several solar masses of matter. The collision of two blast waves causes radiation of an enormous amount of light that is at least ten times brighter than a common supernova.
For the time being, the theory is based on calculations of energy flows that reach Earth from pulsatile objects in the space. However, in the near future we may witness the birth of other supernovas, which will confirm Blinnikov’s ideas. Scientists may be awarded the second Nobel Prize for pulsars. The first one was granted to Hewish alone in 1974. The Nobel commission might consider it unseemly to award such a high prize to a postgraduate. Her advisor did not insist on scientific parity, though there is a precedent in the Nobel Prize history. Jocelyn Bell had to justify her boss for 40 years.
Translated by Julia Bulygina