In our study ofStars

The students will be able to Determine color, temp., brightness

and Size of a starAnd show what they learned by

Interpreting the HR Diagram

WARM-UP

Scientists classify stars based on their brightness (Luminosity)

And Temperature

Classifying Stars

• Astronomers classify stars according to:

• size/mass, • temperature, • color, and • brightness.

• How bright a star or galaxy shines is its brightness or luminosity

Draw this graph in your journal:L

um

ino

sity (Brig

htn

ess)

Temperature

Now add your numbers Along the edge of the

graph

Notice what happens to the numbers as we move from Left to Right.

Now add your numbers Along the edge of the

graph

Increasing Temperature

Now add your numbers Along the edge of the

graph

Hotter Colder

Now let’s look at Luminosity:L

um

ino

sity (Brig

htn

ess)

Temperature

Dim Stars

BrightStars

Increasin

g

Now let’s begin placing our different types of stars

White Dwarfs(Dead Stars

Now let’s begin placing our different types of stars

White Dwarfs(Dim Stars)

Main Sequence Stars(Very stable in their life,Young to middle aged

stars)

White Dwarfs(Dim Stars)

White Dwarfs(Dim Stars)

Our Sun

Star Temperatures Color of a star

indicates its surface temperature

Red stars are the ”coolest” while blue are the hottest

Sun is a yellow star

17

Hertzsprung-Russell Diagram

27.2 The size of stars

• Stars come in a range of sizes and masses.

• Our Sun is a medium-sized star.

• The largest stars, giant stars have a mass of about 60 times the mass of the Sun.

• Which star is hottest supergiant?

• What temperature is Sirius B?

Which star is the dimmest (least bright) on the chart?

Order these stars from hottest to coolest: Procyon, Spica, Sirius B, and Pollux