The Hubble Space Telescope has captured live footage of an exploding star "Refsdal". A prediction was made regarding its explosion and that is exactly what happened.
The Hubble Space Telescope has caught an explosion of a star in outer space. The supernova was slated to occur and it definitely didn’t let the astronomy buffs down. So many stars end their existence with a blast.
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However, very few have actually been caught on camera as they underwent the bang. Mostly, it is just a matter of pure luck. But this time around things were planned.
On 11th December, an image of a supernova was caught in the act of exploding into a thousand million smithereens. It was pinpointed and the explosion occurred right on time as was to be expected.
The supernova had the title of Refsdal. And it had been found in a particular galaxy cluster. The light from the galaxy took some five billion years to reach us. As for the time of the explosion, it was 10 billion years ago.
The probe into Refsdal began in November of this year. That is when scientists noticed four separate images of the supernova. The arrangement was one known as the Einstein Cross.
"While studying the supernova, we realised that the galaxy in which it exploded is already known to be a galaxy that is being lensed by the cluster,” explains Steve Rodney, co-author, from the University of South Carolina.
“The supernova's host galaxy appears to us in at least three distinct images caused by the warping mass of the galaxy cluster.”
It was a sort of universal optical illusion that the astronomers were seeing. As the supernona was being examined, its galaxy was noted down as well. The warping effect of the galaxy cluster was obvious from the start.
The many images that were caught on the telescopic camera showed a rare chance of observing the normally unobservable. The matter – both dark matter and visible matter – are distributed unevenly in the cluster. The light thus plays tricks on the observing eye. The images that reach us are visible at different times.
Other galaxies within the cluster had their relevant data combined with the Einstein Cross a year ago. Thus predictions for the reappearance of the supernova got made. It has appeared once in 1998. But back then it wasn’t seen through a telescope. A few very technical tools were used to make the predictions.
“We used seven different models of the cluster to calculate when and where the supernova was going to appear in the future. It was a huge effort from the community to gather the necessary input data using Hubble, VLT-MUSE, and Keck and to construct the lens models,” explains Tommaso Treu, lead author of the modelling comparison paper, from the University of California at Los Angeles, USA.
“And remarkably all seven models predicted approximately the same time frame for when the new image of the exploding star would appear”.
It did take a huge and gargantuan effort to tie the loose ends together. But it was worth it in the end. The testing of predictions helps sharpen the means we have of observing the cosmos. The Refsdal appearance is just one of several exciting observations which lie in the future for budding astronomers.
“Hubble has showcased the modern scientific method at its best,” comments Patrick Kelly, lead author of the discovery and re-appearance papers and co-author of the modelling comparison paper from the University of California Berkeley, USA.
“Testing predictions through observations provides powerful means of improving our understanding of the cosmos.”