Supernova appearance to help astronomers crack cosmic mystery with ‘precise measurement’

NASA: Hubble telescope captures fading supernova in NGC 2525

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About 10 billion years ago, a star in the constellation Cetus met its fiery demise when it erupted into a cataclysmic supernova. Some of the light from the explosion reached our planet and in 2016 was picked up by NASA’s Hubble Space Telescope as three distinct points of light. Due to a cosmic quirk known as gravitational lensing, the supernova’s light has been going on and off like a faulty lightbulb, and astronomers predict it will reappear to our telescopes sometime in 2037.

According to NASA, this will be the fourth-known viewing of the supernova, which erupted in the galaxy cluster MACS J0138.

Galactic clusters may contain thousands of galaxies of all shapes and sizes, weighing millions and billions times more than our Sun.

Because of their imposing collective mass, galactic clusters drastically warp the fabric of space and time, causing all light passing through to change paths.

This effect is known as gravitational lensing and was predicted by Albert Einstein’s monumental theory of general relativity in 1915.

Gravitational lensing is what caused the Requiem Supernova to appear as three points of light, rather than one, in 2016.

As the supernova’s light passed through the MACS J0138 cluster, it was split and scattered into multiple images.

Even more intriguingly, a comparison of Hubble pictures taken in 2016 and 2019 shows the supernova’s light has disappeared completely.

Gabe Brammer of the Cosmic Dawn Center at the Niels Bohr Institute, University of Copenhagen, in Denmark, said: “Each of the three objects was paired with a lensed image of a distant massive galaxy.

“Immediately it suggested to me that it was not a distant galaxy but actually a transient source in this system that had faded from view in the 2019 images like a light bulb that had been flicked off.”

But the light won’t be gone for good as astronomers predict it will reappear at some point in the next 16 years.

And when it does show up again, scientists think they will have an opportunity to narrow down a cosmic figure that has been hotly debated in recent years – the expansion rate of the universe.

NASA: Supernova explosion changes over 13-year period

American astronomer Edwin Hubble was the first to directly observe how galaxies in every corner of the universe are moving away from one another.

Theoretical physicists have speculated this could be a possibility in the aftermath of the Big Bang.

Today, the expansion is measured at about 2.5km per second per megaparsec.

In other words, for every megaparsec – 3.3 million light-years – from Earth, the universe expands by 73.3 ±2.5 kilometres per second.

The expansion appears to be driven by a mysterious force scientists have named dark energy.

But this is only one of the proposed expansion rates as scientists have been unable to agree on the exact figures.

Different methods of measuring the expansion tend to yield different results and scientists have been trying to narrow down this cosmological phenomenon.

Astronomers will next try to measure the expansion by charting out the dark matter that permeates the MACS J0138 cluster.

The mystery substance, which we are yet to directly observe, is the biggest source of gravity in the universe.

Johan Richard of the University of Lyon in France drafted a map of the dark matter in MACS J0138, based on how it warps the light passing through it.

And the long delays in between the supernova’s light flaring up and then disappearing will help narrow down the elusive figure.

He said: “These long time delays are particularly valuable because you can get a good, precise measurement of that time delay if you are just patient and wait years, in this case more than a decade, for the final image to return.

“It is a completely independent path to calculate the universe’s expansion rate.

“The real value in the future will be using a larger sample of these to improve the precision.”

The supernova is expected to reappear again in 2042 although by then it might be too dark to be visible.

However, NASA’s soon-to-launch James Webb Telescope might be powerful enough to observe the light again.

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