SN Requiem: A Supernova Seen Three Times So Far

Astronomy Picture Of The Day Explore the cosmos Every day, a new image or photograph of the fascinating universe is presented along with a short explanation by an astronomer. 2021 November 2


Explanation: This supernova has been seen three times. When will it be seen a fourth time? If a distant star explodes as a supernova, it's rare that we even see it once. AT 2016jka ("SN Requiem") was a case in point. The exploding star was located behind the center galaxy cluster (MACSJ0138 in this instance). A comparison of Hubble Space Telescope images shows that we actually saw it three times. These three supernova images can be seen in the circles at the bottom of the left frame, taken in 2016. The circles in the right frame were taken in 2019 and are empty as all three images of the supernova have faded. However, computer modeling of the cluster lens indicates that a fourth supernova image should eventually appear in right-hand circle. But when exactly? However, the best models predict that it will occur in 2037. But this date is not certain by two years due to ambiguities in both the mass distribution of cluster lenses and the brightness history from the stellar explosion. Earthlings who live 16 years from now can catch the fourth image with precise predictions and careful monitoring. They may also be able learn more about supernovas and galaxy clusters by making better predictions.