A team of international researchers has made a groundbreaking discovery in the field of astronomy. Using the Atacama Large Millimeter/submillimeter Array (ALMA), they have observed an unusual phenomenon of rebrightening in a supernova known as SN 2018ivc. This is the first time that such a rebrightening has ever been observed in millimeter wavelength radiation.
SN 2018ivc is an intermediate case between two types of supernovae: those of solitary stars and those in close-binary systems. It was found that interaction with an intermediate-distance binary companion about 1500 years before the SN explosion created a large hollow shell of circumstellar medium. At 200 days after the SN, the ejecta flying out from the explosion had yet to reach the shell. Then, sometime between 200 and 1,000 days, the ejecta collided with the circumstellar medium, causing the rebrightening.
The research team, led by Keiichi Maeda of Kyoto University and Tomonari Michiyama of Osaka University, used ALMA to monitor SN 2018ivc as it dimmed for about 200 days after the initial explosion. The results showed that the supernova was an unusual object, which prompted the team to check up on it again, 1,000 days after the explosion.
The presence or absence of a close binary companion can affect the evolution of massive stars. In a close binary system, the binary companion will strip large amounts of material from the SN progenitor long before the final explosion, making the progenitor quiet up until the time of the actual SN. On the other hand, in the case of an SN progenitor with no binary companion or a distant companion, the progenitor will keep most of its initial mass.
This discovery provides important insight into the behavior of supernovae and the impact of binary companions on the evolution of massive stars. It opens up new avenues for further research into the mysteries of the universe.
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