Hertzsprung-Russell Diagram

H-R Diagram

• Compares the temperature, color and luminosity (brightness) of stars on a graph.

• The temperature is the surface temperature of the star

• The brightness of the star is its absolute magnitude

APPARENT MAGNITUDE VS.

ABSOLUTE MAGNITUDE

Apparent magnitude

Absolute magnitude

Measure of the amount of a star’s light received on Earth

Measure of the amount of lighta star actually gives off

STAR PROPERTIES

Color indicates temperature

Hot stars are

Cool stars are

YellowMedium temperature stars are

Blue

Red

White dwarfs

small, hot stars

leftover centers of old stars

Red-Giants

When star runs out of energy, the center shrinks and the outer part expands outward. It will grow very large and cool.

Supergiants

Very massive cool giant star

Main Sequence

Stretches diagonal from the top left to the right bottom

Our sun is an average main sequence star

Blue Supergiants

Very massive blue stars

Quickly use up energy and turn into Giants or Supergiants

Red Dwarfs

Low-mass stars

Oldest stars in galaxy

Putting it all together

http://www.eram.k12.ny.us/education/sctemp/77f43cfb9ae82b830c63fb080599aa31/hr.swf

H-R Diagram AND Life Cycle