Astrophysicists have proposed a new model that explains the unusual properties of the iPTF 14gqr supernova. According to their idea, the predecessor star lost its outer layers due to a small companion, and the explosion itself gave rise to another compact body - a neutron star. Thus, scientists for the first time were able to record the birth of a binary system of similar bodies. The merger of bodies in such a system was first recorded by gravitational waves in August 2017. The results are published in the journal Science.
Usually, a supernova explosion is the explosion of an old star after the thermonuclear fuel has been depleted in its interior. This process is accompanied by a powerful burst of radiation that gradually diminishes over about 17-20 days. Supernova iPTF 14gqr was recorded as part of the survey at the Palomar Observatory in October 2014. It was unusually dull and faded in just a week.
Theoretical models show that the predecessor star iPTF 14gqr was about ten times more massive than the Sun, but during the outburst it ejected only about one fifth of the Sun's mass, although usually much more matter is ejected into space. This behavior of the supernova can be explained by the fact that a significant part of the outer layers was ripped off by the companion of the star before the supernova stage. Theorist Thomas Tauris from the University of Aarhus (Denmark) first considered such a scenario in 2013 and called it an “ultrastripped supernova”.
"This is the first time that we have received convincing evidence of the collapse of the core of a massive star that has so little matter," says co-author of the work, Mansey Casleyval of the California Institute of Technology (USA).
“I think the evidence presented is very compelling,” says Tauris, who was not involved in the work. "In addition, I am personally very happy about this, since I first discovered such supernovae only in theory, so it is truly amazing that observers were able to confirm their existence."
Moments before, during and after the occurrence of the iPTF 14gqr supernova on the outskirts of the spiral galaxy.
Astronomers believe that after the supernova, the system was left with two neutron stars in close orbits or a pair of a neutron star and a black hole. The merger of a pair of neutron stars in such a system was first detected by a gravitational signal in 2017, but it was unclear how such pairs are formed. Supernova iPTF 14gqr shows that they are born close to each other and only get closer over time.