An international group of astronomers watched the first outbreak of a supernova in its kind, which confirms the prediction made about 40 years ago. The results of observation of the residues of the exploded star were published in the journal Nature Astronomy.
theoretically predicted that if the star is in the range of weights of 8-10 suns, then at the end of their life cycle there should be a supernova, which occupies an intermediate position between the formation of white dwarf and a supernova with a collapse of the iron kernel. This type of flashes is called supernova with electronic grip. An electron capture is called one of the types of decays of atomic nuclei, when the proton captures the orbital electron and turns into a neutron, the emitting electron neutrino. Stars, which turn into such supernova, should refer to the super-asymptotic branch of the giants (SAGB) and have a degenerate core consisting of oxygen. Neon and magnesium, and the seizure of electrons with neon and magnesium cores must initiate a kernel collapse.
Flare occurred in the NGC2146 galaxy at a distance of about 31 million light years. Scientists analyzed the data on the explosion of the star and the spectrum of her residues collected in two years, and showed that the supernova 2018ZD, found in March 2018, approximately three hours after the light from the explosion came to the Earth, satisfies all the six supernova criteria with grasp electrons.
So, the predecessor of supernova 2018ZD was a star belonging to the asymptotic branch of the giants (AGB), that is, the late stage of the evolution of the stars of small and medium mass. SAGB is at the upper limit of the asymptotic branch and have some specific characteristics that distinguish them from the rest of the giants. Before the most supernovae, a lot of mass lost, the flash itself was relatively weak with low levels of isolated energy and low radioactivity and a rich neutron active core, and the nebulae had an unusual chemical composition.
Results also suggest that the famous supernova, which occurred in 1054 of our era and caused the appearance of crabovoid nebula, also treated supernova with electronic capture.