Scientists have discovered strong evidence that there are some. big stars They end their existence not with a bang but with a whimper and sink into a swamp. black hole Without the light and anger of a being, their own actions supernova.
To understand why this matters, we need to start with a crash course on stellar evolution. Stars produce energy nuclear fusion There are processes in their cores that convert hydrogen into helium. When there are at least eight times as many stars as stars mass of our sun When the hydrogen supply is exhausted, they instead initiate fusion reactions involving other elements (helium, carbon, oxygen, etc.) until they end up with an inert iron core that requires more energy than it can undergo the fusion reaction. to produce. At this stage, fusion reactions stop and the energy production that sustains the star evaporates. Suddenly gravity is released, causing the core to collapse, while the star’s outer layers bounce back from the contracting core and explode outward; It ignites a supernova that can sometimes shine brighter than an entire star for several weeks. galaxy.
Meanwhile, the collapsing core forms a compact object. This object is usually a rotating object neutron star It is said pulsar – but under certain conditions it can become a stellar-mass black hole. This is the standard story of star timelines. But astronomers are now beginning to come to the conclusion that some stars may produce black holes. without a supernova explosion.
Relating to: One of the universe’s most ‘extreme’ dead stars unexpectedly came back to life
Researchers have noticed the following phenomena from time to time: failed supernovae – stars that begin to shine as if they are about to explode, but then flicker and fade out. Elsewhere, studies of old photographic plates Objects Disappeared and Resurfaced During a Century of Observations The (VASCO) project, led by Beatriz Villarroel, found dozens of stars no longer visible in these ancient plates; It’s as if they disappeared without a trace.
Could these failed supernovae and vanishing stars be evidence that stars were almost completely sucked into the black hole they formed before they had a chance to explode? Maybe some scientists believe this.
“When one looks at a visible star that is completely collapsing, it can be like watching a star suddenly fade out and disappear from the skies just in time,” said Alejandro Vigna-Gómez of the Max Planck Institute. for Astrophysics in Germany expression. “Astronomers have recently observed the sudden disappearance of brightly shining stars.”
Although this idea is still just a theory, it now has strong supporting evidence in the form of a peculiar binary system studied by Vigna-Gómez and his team. The system called VFTS 243, Discovered in 2022 and is located in the Tarantula Nebula. Large Magellanic Cloud; It contains a 25-solar-mass star and a 10-solar-mass black hole, which must have been produced by a cosmically massive star that reached the end of its life relatively recently.
“VFTS 243 is an extraordinary system,” Vigna-Gómez said. “Although VFTS 243 contains a star that collapsed into a black hole, no traces of the explosion were found anywhere.”
For example, the orbits of the star and black hole in VFTS 243 around their common center of mass are still nearly circular. However, supernova explosions are asymmetrical, with slightly more energy produced in one direction than the other, which should create a “birth hit” to the compact object. Such a kick would accelerate the compact object and cause its orbit to widen and become longer. Typically this impact is between 30 and 100 kilometers (19 and 62 miles) per second, but the black hole in VFTS 243 was hit at up to four kilometers (2.5 miles) per second.
The results of birth hits have been observed before in pulsars, but never before in stellar-mass black holes. This is very likely to tell us something about how stellar-mass black holes form, and VFTS 243 is the clearest look yet at the consequences of this process.
Birth strokes are the product of three things: debris expelled from the exploding star, neutrinos from the star’s collapsing core and gravity waves. However, if the supernova had not occurred, there would have been no remnants, leaving only neutrinos and gravitational waves, providing a much smaller hit; This is exactly what we saw in VFTS 243.
If true, it would mean that many of the brightest stars in the universe would end their lives in silent darkness, being dragged into the oblivion of a black hole. This may also be the ultimate fate of the surviving star in VFTS 243 when it reaches the end of its life.
This also has broader implications. The supernova explosion is an element factory. Not only do elements such as oxygen, carbon and nitrogen in the outer layers of a dying star explode. space The intense heat and energy of the supernova shock wave can cause even heavier elements to form in the supernova debris, where they can be formed into new generations of stars and planets. For example, one of the reasons why supernovae stay bright for so long is that the radioactive decay of nickel isotopes produced in the explosion leads to the formation of cobalt and iron.
Related Stories:
— A new approach could help scientists see inside a neutron star
— Dead star ‘glitches’ may reveal origins of fast radio bursts
— Heaviest neutron star ever observed is tearing apart its companion
However, if some massive stars completely collapse into black holes without a supernova explosion, they cannot contribute to the formation and recycling of elements. So cosmochemists will need to incorporate this concept, if it is indeed true, into their models of how elements form and spread through space. Only then can they begin to fully understand the chemical evolution of galaxies, including our own, and how quickly the elements needed to form similar planets are formed. SoilThey may even accumulate their own life, formed from elements produced by exploding stars.
The findings of VFTS 243 were published May 9 in the journal Physical Examination Letters.