If the signs detected by the prodigious space telescope are confirmed, a star up to 10,000 times larger than our sun would have existed in the cosmos.
The James Webb Space Telescope has helped astronomers detect the first chemical signs of supermassive stars, “sky monsters” that glowed with the brilliance of millions of suns in the early universe. So far, the largest stars observed anywhere have a mass around 300 times that of our Sun. But the supermassive star described in a new study has an estimated mass of 5,000 to 10,000 Suns. The team of European researchers behind the study previously theorized about the existence of supermassive stars in 2018, in an attempt to explain one of astronomy’s great mysteries.
For decades, astronomers have been puzzled by the enormous diversity in the composition of different stars packed into what are known as globular clusters. Clusters, most of which are very old, can contain millions of stars in a relatively small space. Advances in astronomy have revealed an increasing number of globular clusters, believed to be the missing link between the first stars and galaxies in the universe.
The great mystery of globular clusters
Our galaxy, the Milky Way, which has more than 100 billion stars, also contains around 180 globular clusters. Why do the stars in these clusters have such a variety of chemical elements, even though they were all presumably born at the same time, from the same cloud of gas?
Many of the stars have elements that would require colossal amounts of heat to produce, such as aluminum, which would require a temperature of up to 70 million degrees Celsius. That’s well above the temperature that stars are thought to get at their core, around the 15-20 million degree Celsius mark, which is similar to that of the Sun. So the researchers came up with a possible answer: the existence of a rampaging supermassive star shooting out chemical “pollution”.
Huge star reactor
Corinne Charbonnel, an astrophysicist at the University of Geneva and lead author of the study, told AFP that a kind of star of that size would gobble up more and more stars.” It would eventually become “like a huge nuclear reactor, continuously feeding on matter , which he will then expel in large numbers,” he added.
This “pollution” will in turn feed young forming stars, giving them a greater variety of chemical components the closer they are to the supermassive star, he added. But the team still needed more observations to back up their theory. Finally, there are indications that they found the long-awaited answer in the galaxy GN-z11, which is more than 13 billion light-years away. It was discovered by the Hubble Space Telescope in 2015 and until recently held the record for the oldest observed galaxy.
Clues and hopes in the cosmos
The James Webb telescope offered two new clues: the incredible density of stars in globular clusters and, most important, the presence of a lot of nitrogen. Truly extreme temperatures are needed to produce nitrogen, which researchers believe could only be produced by a supermassive star. “Thanks to data collected by the James Webb Space Telescope, we believe we have found a first clue to the presence of these stars,” Charbonnel said in a statement. But there is little hope of directly observing this large, supermassive star. Scientists estimate that the lifespan of such celestial bodies is only about two million years, the blink of an eye on the cosmic time scale. However, they suspect that globular clusters existed until about two billion years ago, and could still reveal more traces of the supermassive stars they once hosted. The study was published in the journal Astronomy and Astrophysics this month.