Messy Giant

Big stars tend to be a bit messy. They blow strong “winds” into space, surrounding themselves with dense clouds of gas and dust. These expanding clouds can ram into the material between stars, piling it up to form denser clouds.

Consider Betelgeuse, the bright orange shoulder of Orion, the hunter. It’s well up in the western sky at nightfall, above Orion’s “belt” of three stars.

Betelgeuse is many times heavier than the Sun. That enormous mass squeezes the star’s core tightly, producing intense heat that revs up the nuclear reactions that power the star. Energy from these reactions pushes the surrounding layers of gas outward, causing the star to puff up. In fact, Betelgeuse is about a thousand times wider than the Sun.

The star’s surface gravity is tiny compared to the Sun's, so radiation and magnetic fields drive dense winds of particles from the surface out into space. In a million years, these winds carry enough material to make a star as big as the Sun.

Recent observations hav