The universe is full of mysteries, and the latest discovery by NASA's James Webb Space Telescope (JWST) has unveiled a fascinating one: the Little Red Dots (LRDs). These enigmatic objects, spotted in JWST's data, are compact, dazzlingly bright, and emit a unique combination of red and ultraviolet light. But what makes them truly intriguing is their potential connection to supermassive stars—up to 100,000 or even a million times more massive than our Sun. This raises a deeper question: could these LRDs be the legendary million-Sun stars that relativistic astrophysicists have been pondering for almost 60 years?
The LRDs emerged about 600 million years after the Big Bang and faded away 1.5 billion years later. Early theories suggested that they were wrapped in clouds of gas and dust, giving them their unusually red color. Some also proposed that they could be supermassive black holes feeding on matter at the heart of galaxies, similar to quasars. However, these theories have been challenged by recent scientific papers, which have revisited the idea of supermassive stars.
One of the key figures in this debate is astrophysicist Devesh Nandal from the Harvard College Observatory. Nandal and his colleagues have produced an illustration showing the distinct layers of the 'envelope' created by massive stars, which could be the source of the light detected as LRDs. The scale of a supermassive star is mind-boggling, with our Sun being just a tiny fraction of its mass.
Nandal's research has gained traction, as it provides a comprehensive explanation for various observed features, including spectra, morphology, and chemical signatures. Even competing scenarios are now incorporating supermassive stars as a central driving force. The LRDs are indeed mysterious, as they combine clues that normally don't go together, suggesting that something very bright is hidden inside dense gas.
The spectrum of LRDs reveals clues that challenge current models of young galaxies and typical active galactic nuclei. They don't produce the expected strong X-ray or radio emissions from rapidly growing supermassive black holes. Instead, the case is building for the involvement of truly fantastic stars—about 100,000 times more massive than the Sun. This leads to another intriguing question: where do supermassive black holes come from?
According to current thinking, they form from the collapse of giant stars, which later become supermassive black holes. The latest research seems to support this idea, as it can recreate the existence of thick gas 'cocoons' that make the LRDs appear compact in JWST images. Supermassive stars, being unstable, would undergo wild pulsations, ejecting vast amounts of gas in shells around the star. These stars would eventually evolve into supermassive black holes, just as predicted by long-standing theories.
In conclusion, the discovery of the Little Red Dots by the James Webb Space Telescope has opened a new window into the universe, revealing the possibility of supermassive stars that challenge our understanding of cosmic evolution. As Nandal suggests, these findings may be changing our very eyes, as we witness the birth of a new scientific paradigm.
