The completion of the life cycle of stars can occur in different ways. Some turn into black holes, others are scattered in the nebula. If the star had a very large mass, at her death, the light may appear to be a neutron star – a very compact object about the size of a small city, but has tremendous density. More recently, however, scientists for the first time ever, an unprecedented phenomenon – the birth of the binary system of neutron stars. Their findings are shared in the journal Science.
The phenomenon, called iPTF 14gqr (SN 2014ft) and incident on the edge of a spiral galaxy, located in 920 million light years from us, was first spotted by scientists in October 2014. The event at the time was interpreted by the supernova, but even then it seemed extremely unusual. We wrote about it last year.
To the star becomes a supernova, it must have mass, which is at least slightly greater than the mass of our Sun (rough estimates say about eight solar masses). By the end of its life, a star generates the entire stock of its fuel – hydrogen. The result is a very rapid collapse of the nucleus, generating a colossal Shockwave that throws away all the external layers of the star into space, leaving the core is actually naked. The event is accompanied by a bright flash called a supernova birth. After it remains only a dense neutron star.
When an explosion occurs, the surrounding space is ejected matter of a few solar masses. But the object iPTF 14gqr was truly unique. Scientists explain that the explosion in space was thrown out the matter component only 1/5 solar mass, which shows very weak at the scale of a supernova explosion.
“We have seen the collapse of the core of a massive star, but noted the very low emission of matter. We call this phenomenon Stripped-Envelope Supernova. The probability of such objects was predicted, but we first saw with my own eyes how the collapse of the core and such a small stellar mass ejection,” says astronomer Mansi was Kasliwal from the California Institute of technology.
The fact that the star actually exploded, implies that she had a lot of material, the researchers note, otherwise its kernel would never have reached the state of collapse. Where did the missing mass?
No, not in Narnia. Based on the force of the explosion and the mass itself a supernova, a team of scientists suggests that near the exploding star may be a previously undetected, but very dense object-a companion, possibly a white dwarf, black hole or another neutron star (more likely), which is “stripped” from the companion star is a main part of matter before the supernova explosion.
Computer simulation of the helium star and the neutron star in the same system showed that this is indeed possible. This was confirmed by monitoring data which indicated the presence of dense accumulations of helium in the space around stars and the lack of this substance in the ejection in the supernova explosion. In other words, the companion star literally sucked all its juices, leaving only a thin surface layer of helium, which was thrown out in the space before the supernova explosion.
According to scientists, it creates quite a vivid picture of the birth of double neutron stars. What is even more interesting because both objects are very close to each other, then eventually they will merge in the collision, throwing in the cosmos gravitational waves. When this event happens, astronomers don’t know.
According to researchers, the birth of binary neutron stars should be fairly frequent phenomenon in the Universe, and we do not see them because these events occur very quickly.
“It seems that these explosions represent the only logical model of the formation of systems consisting of pairs of neutron stars or pairs of neutron star plus black hole. At this close location of these objects to each other allows us to become witnesses of their merger,” say the researchers.
To discuss the opening of the astronomers in our Telegram chat.
Astronomers first witnessed the birth of a system of binary neutron stars
Nikolai Khizhnyak