Giant stars were overfed as infants

In the standard model of star formation, protostars develop after a core of gas in a thick cloud of gas and dust collapses under its own gravity. Gravitational potential energy is released as kinetic and therefore thermal energy. Eventually, the temperature and pressure rises to the point when fusion can be sparked off. Then light from the nascent star warms the surrounding gas, strikes it with radiation pressure and causes it to expand outward in a shockwave.

The trouble is, this happens so fast some of the largest stars, which can be as big as one hundred and thirty times the mass of the Sun, don’t have time to accrete enough matter. Scientists have tried modelling the initial conditions every which way they can, but to no avail. Above a certain size, the new star simply blasts everything else away too quickly. However a new study suggests it is actually what comes next that is important.

The expanding shockwaves of several forming stars in a large cluster meet and compress the gas between them into sheets and filaments. Within these sheets and filaments, two things can happen of importance – firstly smaller stars can be formed if there are blobs of high enough size. Secondly, if one of the large stars intercepts a filament, material will be fed into the star, allowing it to grow the rest of the way to its adult size.

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