SIZE MATTERS when it comes to forming a galaxy. Astronomers have discovered the number of stars is probably three times bigger than assumed because many are so small they are difficult to detect.
“As it turns out, the universe thinks small, at least when it comes to star size,” said Dr Charlie Conroy of Harvard University.
He and Yale University’s Dr Pieter van Dokkum discovered the universe is coming down with these pint-sized stars that are only 10-30 per cent the size of our own sun. The problem until now was the objects, known as red dwarf stars, were too small and dim to be seen and so they went unnoticed.
They have revised the census of stars, bumping it up by 300 per cent and changing assumptions in the process. The two publish their findings this morning in the online edition of the journal Nature.
These are based on scrutiny of eight nearby galaxies between 50 and 300 million light-years away from our own Milky Way.
They looked only at the biggest galaxies, elliptical galaxies, which at one trillion stars hold 2½ times the number in the Milky Way. They found the elliptical galaxies were teeming with red dwarfs – with 20 times more than in a Milky Way-type spiral galaxy.
The finding forces a whole range of recalculations, and not just for the total number of stars.
Red dwarfs may make up 60 per cent of the total mass of an elliptical galaxy, which means there is less requirement for mass provided by mysterious “dark matter”.
And if the number of stars increases, so do the planets in orbit around them – and if there are more planets, there are going to be more Earth-like planets with the potential to support life.