Thirty-three years ago, astronomers recorded a supernova explosion, 1987A. And just recently they found a neutron star formed in this cataclysm. This is the youngest such object in the history of observations. For some time, scientists doubted that they were observing exactly a neutron star, but fresh scientific work has provided very convincing evidence of this.
On February 23, 1987, male astronomers (and also female astronomers) received a gift from the Universe. On this day, supernova 1987A was discovered, which exploded in the Large Magellanic Cloud – a nearby dwarf galaxy, a satellite of the Milky Way.
As you know, a star dying in a supernova explosion (or rather, what is left of it) turns either into a black hole or into a neutron star. Scientists were confident that in the case of 1987A, the second option was realized. This was indicated by the flux of neutrinos recorded by terrestrial detectors simultaneously with the light of the flash.
Recall that a neutron star is a celestial body with a diameter of only a few kilometers, which, at the same time, is comparable in mass to the Sun. Due to the monstrous density and the most powerful magnetic field, the matter inside such an object is in states that cannot be reproduced in terrestrial laboratories. Therefore, neutron stars are of great interest to physicists. And, of course, astronomers who seek to figure out the ins and outs of every object and process in the universe.
The 1987A explosion gave researchers the first chance to study the neutron star that formed before their eyes and understand what these celestial bodies are like immediately after birth. All other known neutron stars are much older.
So, the second place belongs to the recently discovered object , which is 240 years old, and even it is surprisingly young compared to its counterparts millions of years old.
Let us clarify that new supernova explosions are discovered regularly and in large numbers , but in galaxies that are too distant to make out the formed neutron star. And the 1987A flare occurred only 168 thousand light years from Earth. It was the closest supernova explosion seen since the invention of the telescope.
Alas, by pointing telescopes at the site of the 1987A flare, astronomers saw only a dense cloud of dust formed during a supernova explosion. For more than thirty years, using increasingly powerful instruments, scientists have tried to discern at least some trace of the central body. And finally they succeeded.
In 2019, the ALMA radio telescope helped astronomers see the supernova remnant 1987A in unprecedented detail. Thanks to this, astronomers discovered that there is a compact and very hot object in the center of the dust cloud. Although the “heater” itself remains hidden behind the dust curtain, the telescope records the radiation of the dust heated by it.
“We were very surprised to see this hot ball formed in a thick cloud of dust in a supernova remnant,” says co-author Mikako Matsuura of Cardiff University. “There must be something in the cloud that heats the dust and makes it glow This is why we assumed there was a neutron star hiding inside the dust cloud.
However, the radiation power seemed suspicious to scientists. Could a neutron star be so hot? Or is there something else lurking in the center of the dust cloud?
“We thought that such a neutron star might be too bright to exist. But then Dani Page and his team published a study that showed that a neutron star could actually be so bright because it is so young,” Matsuura says.
The scientific article , published in the edition of the Astrophysical Journal by Dany Page of the National Autonomous University of Mexico and his colleagues, set the record straight. Experts have shown that the dust-heating object at the center of Supernova remnant 1987A not only could be a neutron star, but could hardly be anything else.
According to the calculations of Page and his co-authors, the temperature of a neutron star 30 years after its birth should be five million degrees. This is just enough to explain the observed heating of the dust.
In addition, the central object is located exactly where the neutron star should have been thrown by the explosion (by the way, at the time of the cataclysm, it was moving at a speed of hundreds of kilometers per second).
Finally, recall that the neutrinos recorded in 1987 indicate that a neutron star was formed during a supernova explosion, not a black hole.
However, theoretically, the central object can be a black hole, onto which a dense stream of matter falls. But this requires a fantastically accurate adjustment of its properties to observational data, which is extremely unlikely. So experts are confident that they have finally “groped” for a newborn neutron star.
We now see the 1987A supernova remnant as it was 33 years after the explosion. Perhaps, after a few more decades, the dust cloud dispersed a little and began to transmit the radiation from the central object. Scientists are looking forward to the moment when these rays will reach the Earth.