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First stars were nasty, brutish and short

protostar.jpgA massive simulation of the formation of the first stars, published in Science this week, shows they started out as tiny ‘protostars’ with a mass just 1% of our Sun. These grew into massive primordial stars which lasted only a million-odd years, compared to our-Sun which could make it to 5 billion.

The NY Times characterises them as “short-lived brutish monsters”.

“These stars are thought to be the first sources of light and also the first sources of heavy elements such as carbon, oxygen and iron,” says Naoki Yoshida of Nagoya University in Japan (Reuters).

The team ran simulations of primordial gas found back in the mists of time, using our the atomic and molecular knowledge of this gas to show protostars can be formed by “primeval density fluctuations left over from the Big Bang”.

In a Perspectives piece accompanying the paper Volker Bromm of the University of Texas, Austin says the work could be a way towards ‘Cosmic Rosetta Stone’ allowing us to understand the previously mysterious process of star formation.

Yoshida et al. have reached a crucial halfway point by pushing their simulation all the way toward the formation of a primordial protostar, the small core inside the collapsing primordial cloud, where for the first time stellar densities, close to that of liquid water on Earth, are reached and where hydrostatic equilibrium is established, the almost exact balance between gravity and thermal pressure.

This protostar will subsequently grow by accreting material from the surrounding envelope until the accretion flow is shut off by the ever more intense radiation emitted by the protostar . The protostellar accretion problem marks the next frontier in the field, but the present study provides a firm foundation for addressing this challenge. The ultimate goal of predicting the mass and properties of the first stars is now within reach.

Image courtesy of David A. Aguilar (CfA) via Science/AAAS


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