The first steps of forming Alpha Centauri is by a nebula. In a nebula gas and dust particles float around. They are free to roam the insides of the nebula. After a while inside the nebula the gas and dust particles starts to collect. They float closer together. The third step is that the density pulls the gas and dust particles . The fourth step of the formation of Alpha Centauri is a protostar forms. A protostar is very small and after a while stars to expand.
The fifth step is that the core becomes very dense because gravity's pressure on the core. The gravitational pull is so strong that it is able to make the core very, very dense. Because of the heat and pressure on the core, fusion begins and creates more and more heat and more light. Fusion is when the Hydrogen and Helium atoms collide. Those atoms that collide create heat and light. When the gas and dust particles come together it's accretion. Accretion is when small objects collide and stick together just like what happens with the gas and dust particles in the nebula.