19. The Hertzsprung-Russell diagram shown is divided into four sections. Section 1
Hertzsprung-Russell Diagram
Section 2
10
:
10*
Section 3
2
10
Luminosity (hun)
3
O
Section 4
ins
102
CLEAR ALL
104
400
200
45
30
100 75 55
Temperature (x10 K)
Which section of the diagram includes the coolest, brightest stars?

The section of the  Hertzsprung-Russell diagram that has the coolest and the brightest stars are the super-giants.

This is a diagram that is used in the field of astronomy to show the absolute brightness of stars against their temperatures.

The super giant stars occur at the upper right of the diagram. In order to find the super giants on this graph, you have to find them at the top right.

Read more on the Hertzsprung-Russell diagram here: