Webb solves mystery associated with the 1987 supernova – 02/25/2024 – Sidereal Messenger

An almost 40-year-old mystery has just been elucidated, thanks to the power of the James Webb Space Telescope. He refers to one of the icons of modern astronomy, the supernova known as SN 1987A.

Supernovae are relatively common occurrences on a cosmic scale – telescopic images of distant galaxies capture these explosions in droves, often resulting from the collapse of high-mass stars. But those that are so close and bright that they can be studied in detail and even seen in the sky with the naked eye are much rarer. Well, SN 1987A was the last of these, observed on Earth in 1987, but reflecting an event that occurred 160 thousand years ago (yes, the distance is 160 thousand light years), in the Large Magellanic Cloud, a satellite galaxy of the Milky Way.

To give you an idea, the last known supernova visible to the naked eye came in 1604, when its appearance was studied and popularized by Johannes Kepler, even before Galileo Galilei pointed the first astronomical telescope at the sky, in 1609. .

The specific type of supernova observed in 1987 is known to result from the death of a high-mass star. When its nuclear fuel, it contracts violently and a rebound effect expels its upper layers into space — this is the detonation we can see. The result is the formation of a nebula around the star, and in the center there remains a lump that could be one of two things: either a neutron star or a black hole.

The final outcome depends on the mass left in the central stellar corpse. If it is much more than twice the mass of the Sun, the gravity is so great that it completely crushes the matter, producing a black hole – an object with gravity so intense that not even the fastest thing in the world, light, can escape it. If it is smaller, gravity is insufficient to cause a complete collapse, but it still degenerates matter to the point of punching electrons inside the atomic nuclei, converting protons into neutrons – hence the name neutron star.

Despite persistent studies of SN 1987A, the gas cloud that surrounds the explosion site prevents observation of the central star, to see what it really is. The doubt lasted until the advent of Webb, which was aimed there on July 16, 2022, with its powerful infrared vision. Analysis of the captured light revealed traces of ionized argon atoms (which lost electrons) in the gas cloud. And they could only have gotten that way by the nearby emission of high-energy photons (particles of light) – something a black hole couldn’t do, but a neutron star could.

The result, produced by the team led by Claes Fransson, from Stockholm University, Sweden, was published in the journal Science and is just the beginning of a more detailed exploration of SN 1987A, which will be observed again by Webb this year. The researchers hope that more data will allow them to know exactly what happens there, which will help to understand how all core-collapse supernovae, such as this one, work. That’s what we have for today, while humanity awaits the detonation of the next supernova in our surroundings, perhaps visible to the naked eye.

This column is published on Mondays in print, in Folha Corrida.

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