All stars.
The HR diagram contains only stars - so everywhere.
Of course they are on the HR diagram. They are simply not on the main sequence.
The brightest stars on the Hertzsprung-Russell (HR) diagram are typically found in the top-left corner, known as the "upper main sequence." These stars are massive and luminous, such as blue supergiants or O-type stars. They have high temperatures and emit large amounts of energy.
main-sequence stars
stars there called stars
stars there called stars
The red dwarves.
The colors of the HR Diagram are:BlueBlue-WhiteYellowOrangeRed-OrangeRed
scatter graph of stars showing the relationship between the stars' absolute magnitudes orluminosities versus their spectral types orclassifications and effective temperatures.
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.
They are very hot stars.
The temperature and luminosity of stars.