A resurrected supernova provides the missing link between two types

March 3 () –

Japanese astronomers have discovered a supernova that presents an unprecedented brightness measured in millimeter wavelengths.

This supposes an intermediate case between two types of supernovae: those of solitary stars and those of close binary systems.

Many massive stars end their lives in a catastrophic explosion known as a supernova (SN). Supernovae rapidly increase in brightness and then fade over the course of several months.

Astronomers have long known that the presence or absence of a close binary companion can affect the evolution of massive stars. In a close binary system, gravitational interactions with the binary companion will pull large amounts of material out of the parent SN long before the final explosion. In these cases, the parent will remain calm until the moment of the NS itself. On the other hand, in the case of a parent NS with no binary partner or with a distant partner, before the explosion of the SN the parent will retain most of its initial mass.

The astronomers wanted to know what happens when the binary is neither too close nor too far away. The discovery came about when an international research team, led by Keiichi Maeda (Professor at Kyoto University School of Science) and Tomonari Michiyama (Joint ALMA Postdoctoral Researcher at Osaka University School of Science), used ALMA (Atacama Large Millimeter/submillimeter Array) to observe a supernova known as SN 2018ivc as it dimmed for about 200 days after the initial explosion.

The results showed that SN 2018ivc was an unusual object, so the team decided to check it again, some 1,000 days after the explosion. They found that the object was getting brighter, the first time this phenomenon had been observed in millimeter-wavelength radiation. reports the website of the ALMA telescope in Japan.

Comparison with numerical models suggests that interaction with an intermediate distance binary companion about 1,500 years before the SN explosion created a large hollow circumstellar medium layer. 200 days after the SN, the ejecta that were ejected from the explosion had not yet reached the envelope. Then, sometime between 200 and 1,000 days ago, the ejecta collided with the circumstellar medium.

These results were published in The Astrophysical Journal Letters on March 1, 2023.