IIP-type supernova research

IIP-type supernova research

Scientists have investigated SN 2015ba IIP-type supernova, showing a long plateau on the light curve. The new study reveals important information about the properties of the explosion, which can help improve our understanding of IIP-type supernovae.

Based on the shape of the light curves, astronomers usually divide Supernova II into two classes. Type II-L - linear supernovae with a rapid linear decline after maximum luminescence. But the II-P (plateau) remain bright for a long time interval after the maximum point. This plateau on the light curve usually lasts about 100 days.

It is believed that the IIP comes from the precursor stars, which retain a significant number of layers of hydrogen (more than 3 solar masses) before they are released in the form of a core collapse. For decades, scientists have studied this type, but some properties are still difficult to explain.

IIP-type supernova research

Above: SN 2015ba's broadband light curves are shifted arbitrarily for clarity. Below: light curve V-band SN 2015ba compared to other IIP-type

SN 2015ba was first noticed on November 28, 2015 on the territory of the galaxy IC 1029 at a distance of 100 million light years from us. Researchers at the University of Delhi (India) began observing the object 3 years after its discovery. The photometric and spectroscopic observation company took almost 9 months. Used 8 ground-based telescopes around the world. The survey showed that SN 2015ba demonstrates an amazingly long plateau, lasting about 123 days. The absolute value of the V-range reached -17.1 50 days after the explosion. It turned out that the production of one of the nickel isotopes (56Ni) was much lower than in the similar supernova SN 2004et. They also analyzed the evolution of temperature after the explosion, showing that in the early epoch the figure reached 20,000 K, in 50 days it was reduced to 6,300 K, and in the late epoch it was 4,800 K.

The findings state that the hydrodynamic and analytical modeling of SN 2015ba hints at a massive predecessor, whose mass before the explosion was 25 times larger than the solar one. But nebular supernova spectra do not support this hypothesis because they exhibit a low level of oxygen.

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