The reason why the winds that blow from the subtropical high pressure system is called the trade wind is because in the era of sailing ships,regions of constant winds were much were appreciated. They made trade around the world possible. That's the reason why it's called the trade winds:)
The protostar is a new star that is formed at the end of the Hayashi track and is luminosity temperature relationship of infant stars that are less than M 3. The protostar ends its period and becomes a Tauri star that is extremely luminous.
After which the main sequence of the stars are formed is the next stage in stellar evolution and is dependent on its mass like the sun after this period the star turn red as it has a hydrogen-rich core and it starts to branch out displaying extreme density.
The last stage is the white dwarf star as the star has degenerate and left is the exhaust core which is very dense.
