The star that DIED TWICE
This supernova “breaks everything we thought we knew”
Like a celestial horror villain, an exploded star has burst back to life after 50 years. This supernova, which exploded in 2014 but only recently faded, may be the revived remnant of a previous explosion witnessed in 1954.
In September 2014, the intermediate Palomar Transient Factory team at the University of California, Santa Barbara (USCB) discovered a new supernova in a distant galaxy named iPTF14hls. At first it appeared to be a run-of-the-mill Type II-P supernova, one caused by the rapid collapse of a massive star, and should have dimmed after 100 days or so. Instead, after a few months it began to grow in brightness, and remained bright for around 600 days.
“Supernova iPTF14hls may be the most massive stellar explosion ever seen,” says Lars Bildsten, director of USBC’s Kavli Institute for Theoretical Physics. “For me, the most remarkable aspect of this supernova was its long duration, something we have never seen before. It certainly puzzled all of us as it just continued shining.”
When consulting archival data, the team found that a supernova had previously been seen in 1954 in the same location. Somehow, the star had survived to explode again 50 years later. This earlier explosion could be an important clue to the supernova’s true identity.
Some researchers suggest that this is the first observed example of a pulsational pairinstability supernova. These occur when massive stars become hot enough to convert energy into matter and antimatter, creating an explosion that blows off the star’s outer layers while leaving the core intact. The process could repeat itself for decades.
“These explosions were only expected to be seen in the early Universe and should be extinct today,” says Andy Howell who leads the supernova group at the Las Cumbres Observatory. “This is like finding a dinosaur still alive today. If you found one, you would question whether it truly was a dinosaur.”
However, it could be that iPTF14hls is a completely new type of supernova.
“This supernova breaks everything we thought we knew about how they work,” says Iair Arcavi from UCSB, the study’s lead author. “It’s the biggest puzzle I’ve encountered in almost a decade of studying stellar explosions.” https://lco.global/news