A star is not considered born until the process of nuclear fusion begins.

Here's why:

* Stars form from giant clouds of gas and dust. These clouds collapse under their own gravity, forming a dense core.

* As the core collapses, it heats up. This heat eventually reaches a point where the pressure and temperature are high enough to start nuclear fusion.

* Nuclear fusion is the process where hydrogen atoms fuse together to form helium. This process releases enormous amounts of energy, which is what makes stars shine.

So, while a star might go through several stages of formation before nuclear fusion begins, it's not considered a true star until that point.