A new supernova discovery offers an intermediate form between two types of supernovae: those of solitary stars and those in close binary systems. Astronomers have discovered a supernova showing unprecedented brightness at millimeter wavelengths.

Long-term research has shown that the existence or absence of a nearby binary star can influence the evolution of large stars. Because of gravitational interactions with the binary companion, large amounts of material will be stripped from the SN precursor long before the final explosion in a near-binary system. Under these circumstances, the progenitor will remain silent until the actual SN. On the other hand, an SN progenitor will retain most of its original mass before the SN explosion if it has no binary or external companion.

What happens if the binary number is not too close and not too far?

This question puzzles astronomers.

An international research team, led by Keiichi Maeda (professor at the Graduate School of Science, Kyoto University) and Tomonari Michiyama (ALMA Joint Postdoctoral Fellow at the Graduate School of Science, Osaka University), presents a result of long-term monitoring of the peculiar Type IIL SN 2018ivc with ALMA.

They monitored SN 2018ivc as it dimmed about 200 days after the initial explosion. The team decided to re-track SN 2018ivc about 1,000 days after the explosion, because the results indicated it was an unusual object. For the first time, using millimeter wavelength radiation, they discovered that the object lit up again.

A massive concave shell of circumstellar medium may have been produced by interaction with a medium-range binary companion some 1,500 years before the SN explosion, according to comparison with computer modeling. The ejecta from the explosion had not yet reached the shell 200 days after the SN. Then the ejecta collided with the circumstellar medium sometime between 200 and 1000 days later.

Magazine reference:

  1. Keiichi Maeda, Tomonari Michiyama et al. Resurrection of Type IIL Supernova 2018ivc: Implications for a binary evolutionary sequence linking hydrogen-rich and hydrogen-poor progenitors. The Astrophysical Journal Letters. DOI 10.3847/2041-8213/acb25e