The missing link between supernovae and black holes has been observed for the first time: thanks to the discovery of a stellar explosion in a nearby galaxy by an amateur astronomer, it was in fact possible to follow the event 'live', demonstrating that the death of massive stars actually generates black holes or neutron stars, the most compact and enigmatic objects in the universe. The result, published in the journal Nature by a group of researchers led by Israel's Weizmann Institute of Sciences, was made possible thanks to a series of instruments on the ground and in space, such as the Very Large Telescope and the New Technology Telescope located in Chile, both of the European Southern Observatory.
When massive stars reach the end of their lives, they collapse under their own gravity so rapidly that a violent explosion known as a supernova ensues. Depending on the mass of the star, what remains will be either a neutron star or a black hole. Astronomers have found many clues that suggest this chain of events, but they have never seen it in real time. This time, researchers led by Ping Chen got lucky: in May 2022, a supernova was discovered in the nearby galaxy NGC 157, located 75 million light-years away.
The authors of the study realized that the object left after the explosion orbits together with a companion star: the theft of energy that the latter suffers every time the other approaches it can in fact only be due to an invisible neutron star, or perhaps a black hole. "Our research is like solving a puzzle," says Chen: "When all the pieces fit together, they lead to the truth." However, there is still much to be revealed about this enigmatic pair, including what happens next: next-generation telescopes such as ESO's Extremely Large Telescope, due to go into operation by the end of this decade, will shed light on these aspects.
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