A star’s apparent brightness is based on what?

Its absolute brightness and its distance from Earth

Where on an H-R diagram are most stars located?

The main sequence

What characteristics are plotted on H-R diagrams?

Luminosity versus surface temperature

What letters are in the spectral class?

O B A F G K M

What determines a star’s color, luminosity, and temperature?

Mass and composition

What happens to stars when they begin fusing elements heavier than hydrogen?

They become giants or supergiants

Which of the following characteristics CANNOT be determined using an H-R diagram?

Distance from Earth

What is the easiest element for stars to fuse?

Hydrogen

Where is our Sun on the H-R diagram?

Main sequence

What is a star color?

Yellow, Blue, White