Whilst the surrounding matter is falling into the central region, it is considered to be in the protostar stage and thus is not on the HR diagram However, when the surrounding gas/dust envelope disperses and the accretion process stops, the star is then considered as a pre-main sequence star. In the HR diagram, the star would then appear on the stellar birthline at the bottom right hand corner.
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 main reason that the HR Diagram is so useful and important to scientists is, you can tell the size of the star by plotting it on the HR Diagram. The different sizes of stars form a pattern on the HR diagram.
All stars.