Deep Underground, A Telescope May Soon Detect Ghosts Of Stars That Died Before Earth Existed

(MENAFN- The Conversation) Imagine looking up at the night sky and seeing a star suddenly burst into a blaze of light brighter than anything nearby. A flash so bright that it briefly outshines an entire galaxy before fading forever.

This violent fate is rare: fewer than about 1% of stars are big enough to end their lives this way. Indeed, these dramatic explosions only occur in so-called “massive stars”. These are stars with a mass roughly eight times or more that of the Sun.

But these cosmic explosions, known as supernovae, have naturally fascinated astronomers for centuries. In 1572, for instance, Danish astronomer Tycho Brahe observed a supernova explosion so bright that it could be seen with the naked eye for two years.

Yet what we can see with our eyes, or even with powerful telescopes, when these stars die, is only a tiny fraction of the story. Because most of the energy from a supernova is carried away by neutrinos, these are nearly invisible particles often called “ghost particles” because they pass through almost everything in their path.

Scientists are now finally on the verge of seeing these ghostly messengers. With the help of an extremely powerful telescope buried deep underground in Japan, astronomers may be able to catch a glimpse of these stellar“ghosts” – and with it the remnants of explosions from stars that died as long as 10 billion years ago.

Particles from before time

And there’s a really good chance that scientists might be able to finally see these ghost particles this year. This is largely due to Japan’s Super-Kamiokande telescope receiving an upgrade, which significantly enhances its ability to detect supernova neutrinos.

For me, as a particle astrophysicist, this would probably be one of the most exciting scientific achievements in my lifetime. Indeed, it would mean we could see particles that were produced even before the Earth itself existed, as the telescope is now sensitive enough to catch the faint“glow” of all the exploding stars in the universe.

This is all possible because neutrinos almost never interact with anything. They have no electric charge. So they can travel through space – and even through entire planets – without being absorbed or scattered, so almost nothing can stop them.

In fact, billions of these ghostly particles are passing through your body every second – and you don’t even notice – and some of them have been travelling for more than 10 billion years to get here.

When a star dies

Big ideas lead to big questions, and one such question astrophysicists are trying to figure out is what remains after the explosion of such a star.

Does the collapsing core become a black hole? Or does it form a different type of star known as a neutron star, which then slowly cools over time? A neutron star is an incredibly dense object, only about 20 kilometres (12 miles) across, roughly the size of a large city or about the length of Manhattan.

If scientists are able to detect the combined signal from all the supernovae that have ever occurred, it would bring us closer to being able to answer these questions. It would also allow us to study the deaths of stars across the entire history of the universe, using particles that have been travelling toward us for billions of years without ever stopping.

Supernovae are rare in our galaxy, happening only once every few decades. But across the universe, a massive star explodes in a supernova roughly once every second. When they explode, they release enormous energy: only about 1% is visible light, while 99% escapes as neutrinos.

Even though these neutrinos are almost invisible, they carry the story of every star that has ever exploded – and now, for the first time, we may be able to catch them.

So if 2026 does bring the first clear detection, it will mark a new era in astronomy. For the first time, we won’t just observe the brilliant explosions of nearby stars, but the collective story of all the massive stars that have ever lived and died.

And it all starts with a telescope buried deep underground in Japan, patiently watching for the faint, ghostly glow of the universe’s oldest explosions.

This article was commissioned as part of a partnership betweenVidenskab and The Conversation. You can read the article in Danish.

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