Asked by: Alex Round, London
In general, distances between stars are so vast that it is unlikely that any two will ever meet and collide. But in some places, notably in globular clusters, stars can be crowded together much more tightly and may well collide with each other. Many clusters contain very large, hot stars known as ‘blue stragglers’, which should have detonated as supernovae billions of years ago. Astronomers think these stars formed more recently as the result of collisions and mergers of normal stars. It is also probable that stars collide in other star-rich places such as the central regions of galaxies. Some binary stars can coalesce as one star reaches the end of its life, expands and consumes its partner.