Protostars are found in the lower right portion of the Hertzsprung-Russell diagram, specifically in the region known as the T Tauri phase. This is where stars are still in the early stages of formation and have not yet begun sustained nuclear fusion in their cores.
The HR diagram contains only stars - so everywhere.
Of course they are on the HR diagram. They are simply not on the main sequence.
Protostars was created in 1971.
Protostars has 271 pages.
All stars are formed from protostars.
The ISBN of Protostars is 0-345-02393-5.
HR diagram
The red dwarves.
Up at the top right. If you look on the Australian Telescope National facility website, their HR diagram shows this clearly.
The Hertzsprung-Russell diagram helps scientists understand the life cycle of stars by showing the relationship between a star's luminosity and temperature. It enables astronomers to classify stars based on their evolutionary stage and predict their future evolution. This diagram is essential for studying the properties and behavior of stars within galaxies.
All stars.