Will a supernova in the Milky Way be visible from Earth in the next 50 years?

The good news is that they have already calculated that the chances of such a supernova being detected by telescopes in the form of infrared radiation are almost 100 percent. The bad news is that the chance of the supernova being visible to the naked eye in the night sky is much lower - only 20 percent or less.

Astronomers from Ohio University have calculated the odds that within the next 50 years a supernova will occur in our home galaxy and be visible from Earth.

The good news is that they have already calculated that the chances of such a supernova being detected by telescopes in the form of infrared radiation are almost 100 percent. The bad news is that the chance of the supernova being visible to the naked eye in the night sky is much lower - only 20 percent or less.

Still, this is good news for astronomers, who, unlike the rest of us, have powerful cameras that scan every point in the sky instantly using infrared radiation. For them, this research indicates that they have a good chance of doing something that has never been done before: detect a supernova fast enough to observe what happens in the early stages of the death of a massive star. The supernova phenomenon occurs when very large stars exhaust all their nuclear fuel and their cores collapse, just before the star violently explodes and throws most of its mass into space.

"We see all these stars about to explode as supernovae in other galaxies and we don't understand how it happens. We think we know, we say we know, but it's not really 100 percent true," said Christopher Kochanek, professor of astronomy at Ohio State University and a researcher in the field of observational cosmology. According to him, today there are advanced technologies that have led to a situation where we can learn more about supernovae if we can catch the next supernova in our galaxy and study it with all the tools at our disposal."

The results of the study were published in the Astrophysical Journal.

Kochanek explained how the technology makes the study of supernovae in the Milky Way possible. "Now astronomers have sensitive neutrino detectors (particles emitted from the collapsing core of a star) and gravitational waves (generated by the oscillations of the star's core), which can detect any supernova occurring in our galaxy. The question is whether we can actually see light from a supernova, that's another question because we live in a galaxy full of dust. Soot particles like those emitted from diesel trucks that absorb the light and may hide the supernova from our field of vision."

"Every few days, we have the opportunity to observe supernovae that occur outside our galaxy," said PhD student Scott Adams, "although we have learned a lot from them, a supernova in our galaxy would have shown us much more. The neutrino detector and the gravity detector are only sensitive enough to measure within our own galaxy, where we believe that supernovae occur only once or twice a century."

Adams added: "Despite the ease with which astronomers detect supernovae occurring outside our galaxy, it is not obvious that observations of a supernova occurring inside our galaxy will be possible because it is full of dust that dims the visible light emitted by stars near the center of the galaxy. Infrared light dims much less than visible light.
By weighing all these factors, the astronomers determined that there is an almost 100 percent chance of capturing a supernova in the Milky Way within the next 50 years.

The astronomers' plan takes advantage of the fact that supernovae emit neutrinos immediately after the explosion begins, but do not emit infrared or visible light minutes, hours, or even days later.

Thus, in the ideal scenario, neutrino detectors such as Super Kamiokande (Super-K) in Japan would provide an alert as soon as they detect a neutrino, pointing to the direction from which the particles came. Infra-red radiation detectors will be able to focus on the suspect area almost immediately, thus allowing the supernova to be observed before the brightening begins. Gravitational floats can do the same.

But given the fact that not all neutrino particles come from supernovae - some come from nuclear reactors, from the Earth's atmosphere or from the sun - how will the detector know the difference? A supernova will produce short bursts of neutrino particles so that they are detected a few seconds apart. But rare malfunctions in the detectors' electronics can cause the same phenomenon, explained John Beecom, professor of physics and astronomy and director of the Center for Cosmology and Particle Astrophysics at Ohio State University. "We need to find a way to immediately say that the particles indicate a supernova," he said.

He and his colleague Mark Waging, an American neutrino expert working at Super K, pointed out a decade ago the way to do this. Now Waggins and others have built a scale model of a special type of neutrino detector in a new underground cave in Japan.

As co-authors of the article in the Astrophysical Journal, Waggins and Bicom described the new detector, known as EGADS (RT Evaluating Gadolinium's Action on Detector Systems). At 200 tons, EGADS is much smaller than the Super K detector, which weighs 50 tons, but both contain tanks of water in an almost completely pure state.

In the case of EGADS, the researchers added a tiny amount of the element gadolinium, which helps detect neutrino particles coming from a supernova in a special way. When a neutrino from a milky way supernova enters the tank, it can collide with water molecules and release energy and some neutrons. Gadolinium has a strong attraction to neutrons, and will absorb them and emit a neutron of its own. The result will be one detection signal, after which a neutron with a much weaker energy will be absorbed - a weak heartbeat inside the container for each neutrino detected. According to the two, this signal will increase the confidence that these are particles originating from a supernova. The success of the experiment caused the people of Super K to add gadolinium to their tank by 2016, which will be able to measure the direction of the neutrinos and increase its sensitivity.

For those hoping to see the supernova in person, the odds are extremely low and depend on our latitude on Earth. The last time this happened was in 1604, when Johannes Kepler noticed a bright supernova that occurred at a distance of about 20 light years in the "Serpent Bearer" group, which was visible in the night sky in northern Italy.

According to Adams' calculations, the probability that a supernova in our galaxy will be visible to the naked eye from somewhere on Earth within the next 50 years is about 20-50 percent, with those living in the southern hemisphere having a higher chance since they can see more parts of our galaxy in the sky The night. The chances decrease as you head north. In Columbus, Ohio, for example, the chance can drop below 10 percent.

"The odds of seeing a spectacular display are not in our favor, but it's still an exciting possibility!", he concluded. "Since the chance of a supernova for the Milky Way is small, only one or two in a hundred years, it would be a shame to miss it. The research aims to improve the chances that the scientists will be ready for a once-in-a-lifetime scientific event," said Bicom.

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