Science
Most of the stars that will one day exist have already been born, scientists have announced.
An international team of astronomers has studied the changes in star formation since the earliest days of the universe using three telescopes: the British Infrared Telescope, the Subaru Telescope and the Very Large Telescope.
Based on known facts, they found that half of all existing stars were created about 9-11 billion years ago, and the other half in subsequent years. This suggests that the number of new stars born has been drastically reduced to the point that 95 percent of all stars in the universe have already been born.
How the universe works: stars
We know that many stars, including our own star, the Sun, are likely to have formed from dust left over from the explosion of earlier larger stars. Scientists could not figure out exactly how many stars the universe gave birth to compared to the number that appeared in later years, as at one point there was a sharp decline in the creation of new stars.
Using the telescope, astronomers looked for alpha particles emitted by hydrogen atoms (often found in star formation in the form of bright red light) in vast areas of the sky.
The analysis showed that star production has been steadily declining over the past 11 billion years.
“We live in a world where old stars predominate. All major actions in the universe took place billions of years ago,” they explained.
The first generation of stars were incredibly big — hundreds of times larger than our Sun. They quickly burned down, releasing dust that later formed stars and planetary systems.
According to the study, in a few billion years, humanity will be able to watch the birth of the last star, if it lives.
The biggest star in the universe
When we look at the sky, the stars look very small. In fact, stars can reach unimaginably huge sizes. As you know, our star, the Sun, is 100 times larger than planet Earth. But there are stars that will make our Sun look like a grain next to it.
The biggest known star in the universe is VY Canis Majoris, a hypergiant that lies 5,000 light years from Earth. It is almost 3 billion kilometers in diameter. If you put it in the solar system, its surface would orbit Saturn, and it would take 8 hours for light to travel around it in circles.