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.
Of course they are on the HR diagram. They are simply not on the main sequence.
The HR diagram contains only stars - so everywhere.
Protostars was created in 1971.
Protostars has 271 pages.
Nebulae themselves are not directly plotted on the Hertzsprung-Russell (HR) diagram, which is a graphical representation of stars based on their luminosity and temperature. However, nebulae are often the regions where stars form, and the stars that emerge from these nebulae can be represented on the HR diagram. The HR diagram primarily focuses on the evolutionary stages of individual stars rather than the nebulae from which they originate.
The ISBN of Protostars is 0-345-02393-5.
All stars are formed from protostars.
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.