ASTRON 1010 Chapter Notes - Chapter 13: Brown Dwarf, Degenerate Matter, Binary Star
Document Summary
A star is born when gravity causes a cloud of interstellar gas to contract to the point at which the central object becomes hot enough to sustain nuclear fusion in its core. Stars are born in cold, dense clouds of gas whose pressure cannot resist gravitational contraction. Two things that help gravity win out over pressure is higher density and lower temperature. Observations confirm the idea that stars are born within the coldest and densest clouds, usually called molecular clouds because they are cold enough and dense enough to allow atoms to combine and form molecules. A molecular cloud fragment heats up as gravity makes it contract producing a protostar at its center. The dense center of the cloud fragment is now a protostar-the cloud of gas that will become a new star. Conservation of angular momentum ensures that protostars rotate rapidly and are surrounded by spinning disks of gas.
