Life beyond the snowline

摘要

MENTION THE snowline and most people's thoughts turn to mountains. We're all familiar with alpine scenes showcasing stunning mountain peaks permanently shrouded in snow. But to an astronomer, snowline has another meaning - one crucial to our understanding of how planetary systems form. The accepted model for the formation of stars and their planets starts with a cloud of gas and smoke-like dust, which collapses under its own gravity. The gas is mostly hydrogen, and the heat of compression generated by the collapse eventually triggers nuclear fusion, which is the process by which stars shine. But the gas and dust also flatten out to form a swirling disc around the infant star, and it's here that planets form.