The stars align: Israeli researchers track a supernova in real time
Weizmann scientists chronicle the earliest stages of a supernova.
This composite image of the Crab Nebula, a supernova remnant,
was assembled by combining data from five telescopes spanning nearly the
entire breadth of the electromagnetic spectrum.Scientists from the Weizmann Institute of Science in Rehovot have gotten the most complete look at a supernova ever, watching and tracking a star’s explosion in real time, as noted in a new study.
This discovery is a major step forward in our understanding of one of the most important phenomena in the universe.
The findings of this study were published in the peer-reviewed academic journal Nature.
To put it less simply, they represent a key part of the greater cosmic cycle of life, creation, death, and expansion.
Stars of all kinds are fueled by this energy production in their cores, which sees energy made by nuclear fission fusing lighter elements to form heavier ones. It is this process that keeps the star hot, allowing gases to expand while simultaneously drawing its mass toward the core in a delicate gravitational balance.
When a star can no longer produce energy, it dies. The larger stars, which are now filled with heavy elements, will unleash a powerful explosion known as a supernova. This fuses some of those heavy elements together to make even heavier ones, and all of them get blasted out into the cosmos.
ASTROPHYSICIST AVISHAY GAL-YAM and researcher Ido Irani look at a
screen in their laboratory at the Weizmann Institute of Science in
Rehovot, last week. (credit: Sebastian Rocandio/Reuters)This process is essential to the function of the universe, allowing everything to keep expanding and ultimately sending forth the building blocks of the universe’s continued expansion.
In other words, everything in the universe is made of stardust, and supernovas are what send that stardust out there to accumulate and make new things.
The remnants of that star are still there, condensing together to form either a neutron star or a black hole.
Studying supernovae has given scientists a wealth of information about the universe. As time has gone on, the library of academic literature on supernovas has only grown even more extensive, especially as technological advances have helped scientists track down supernovae occurring in faraway galaxies.
But there is still a very big problem: How do you predict if a star will go supernova?
Throughout our history, barring the times when supernovae were visible in the skies above Earth in the distant past, scientists have been unable to determine in advance when a star will explode.
Sure, when a supernova actually happens, it becomes pretty obvious – these explosions are quite literally universe-shaping after all. But all scientists can do is study the aftermath, seeing what the blast left in its wake.
But the scientists from Weizmann were able to witness a supernova in real time. So, how did they manage to do the impossible and predict if a star was going to explode?
The answer is extremely simple: They didn’t.
Back in 2023, the researchers, part of Prof. Avishay Gal-Yam’s group at the Weizmann Particle Physics and Astrophysics Department, had been hoping to use NASA’s Hubble Space Telescope for data on supernova interactions. Instead, they witnessed not only a supernova but one that was relatively close by: A red supergiant in the neighboring Messier 101 galaxy.
BUT THE old adage “Man plans, God laughs,” could easily be reworded as “Man plans, Supernova has poor timing,” because it came at a very inconvenient moment.
The supernova was discovered on a Friday, which in Israel is already the weekend, and just before the weekend in Baltimore, where Hubble’s operations center is located. The one who found it was a Japanese amateur astronomer, Gal-Yam explained, noting he was browsing his email while sitting at home that Friday. Seeing this, he promptly emailed his students.
Complicating this further, this took place just before one of the study authors, PhD student Erez Zimmerman, was set to get married.
“I was about to get married on Sunday. I had a bunch of guests coming over from abroad and we went to a bar together,” Zimmerman recounted. “A stream of emails started coming into my smartphone while I was still in the bar. I looked at the email and I realized that this was exactly the supernova I was waiting for to observe with the Hubble Space Telescope. This was a day and a half before the wedding... I went to the car with my fiancée and I told her, ‘Uh, look, I think there’s a supernova I need to work on.’ She was like: ‘Hubble?’ And I was ‘Yeah, Hubble.’”
Gal-Yam said, “It’s very rare, as a scientist, that you have to act so swiftly. Most scientific projects don’t happen in the middle of the night, but the opportunity arose, and we had no choice but to respond accordingly.”
This was a race against time, all the data needed to be taken as quickly as possible, and they had to perfectly orient Hubble to just the right spot to collect the data before the NASA Hubble operators left for the weekend.
Despite the horrible timing, and Hubble’s own sluggishness, the researchers did the impossible. Within 50 hours, Hubble was observing the supernova – the first time scientists have ever gotten there so quickly.
But what about the wedding? It still went ahead, and many of the researchers came a mix of exhausted and energized due to all their work.
Zimmerman explained that he worked hard to get everything ready the day of the wedding, and then he got the confirmation from NASA that they would be observing the supernova. “So I was aware this would be happening the day after my wedding,” he noted.
Hubble even confirmed on social media that it was taking a look at the supernova for Zimmerman.
So what did they learn?
Interestingly, Hubble had observed and gathered data from this particular part of the universe many times already. As such, there was a huge amount of available data on it in NASA’s archives.
The researchers were able to see the red supergiant star in its final days, creating an almost perfectly complete portrait of what a supernova is: A star’s death.
But remember: A supernova leaves something behind, usually a neutron star or a black hole. What about that?
Regarding this, the researchers noted something interesting.
In a statement, Weizmann PhD student Ido Irani noted that when calculating the density and mass of circumstellar material before and after the supernova, something was missing: Specifically, lots of mass.
In a statement, Weizmann PhD student Ido Irani noted that when calculating the density and mass of circumstellar material before and after the supernova, something was missing: Specifically, lots of mass.
But overall, the researchers were able to witness a supernova like never before, which in turn means they are able to, in retrospect, study what a star was like in its final days, rather than resort to what amounts to gathering forensic evidence from a supernova.
Since that star was so close, the available data is very high-quality.
But there’s still more to discover. The supernova isn’t over yet, and new data is still coming in. Where is all the material going to go? What will it eventually make? Well, it was the materials spread by supernovae in the distant past that eventually created the Milky Way, our solar system, Earth, and all life.
“There’s a saying that we’re all stardust, and it’s true, actually, because every element in our body [originates] in a star,” Zimmerman said. “And when stars explode, they emit this material away, and eventually it ends up in us.”
Given all of that, the possibilities could be practically endless.
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