Recently, scientists conducted photometric and spectroscopic observations of SN 2018byg. This is an unusual Ia-type supernova. Conclusions suggest that a double detonation of a massive helium shell led to a cosmic explosion.
Supernovae are energetic stellar explosions, mostly of type I or type II. It all depends on the nature of the spectra and the light curves. Type I SNe is divided into three classes: Ia, Ib and Ic. It is believed that the Ia-type is created after the explosion of a white dwarf in a double star, when it exceeds the Chandrasekhar limit (1.4 solar masses).
Detection field and host galaxy for ZTF 18aaqeasu. An archived SDSS image of the site is shown above, and a snapshot from WASP is below. The location of the transition process is marked by a white circle. It is projected with an offset of 17.2 inches.
For the first time, SN 2018byg (ZTF 18aaqeasu) was noticed on May 4, 2018. This is one of the most interesting supernovae I-type, so the scientists decided to conduct a comprehensive observation using various ground-based telescopes and spacecraft. Due to this, it was possible to better understand the origin of the stellar explosion. The researchers believe that the supernova explosion was caused by the detonation of a helium shell on a white dwarf. The survey showed that the outer layers of the release are extraordinarily rich in elements of the iron (Fe) group, which indicates the decay of radioactive elements in the external release. The analysis also demonstrated that peak photospheric spectra are endowed with red color, which is unusual for Ia-type supernovae.
To explain the strange characteristics of the SN 2018byg, scientists compared the data with different models. The hypothesis of a massive detonation (0.15 solar mass) of a helium shell on a white dwarf with 0.75 solar mass turned out to be the most plausible. Researchers note that double explosions of helium shells are rare, so a supernova can be considered unique.