HR Diagram

Characteristics of Stars

Temperature/Color

Mass

Luminosity

• Absolute Magnitude• Apparent Magnitude

The Spectral Sequence

Bluest Reddest

Hottest Coolest50,000K 1300K

O B A F G K M L

Oh Boy, an F grade kills me, Louis!

The mass of a star determines the length of its life cycle (how long

will it burn).

Sun-like StarsUp to 1.5 times the mass of the Sun

Huge StarFrom 1.5 to 3 times the mass of the Sun

Giant Star Over 3 times the mass of the Sun

Stellar Nebula(nursery)

Sun/main sequence star

Massive Star ( Huge & Giant)

Red Giant

Red Supergiant

Planetary Nebula

Supernova

White Dwarf

Neutron Star

Black Hole

Protostar

Star sizeDistance from EarthStar temperature

Variables which affect a star’s brightness:

Absolute Magnitude

• Apparent Brightness: The amount of light received on Earth from a star.

Apparent Magnitudevs.

• Actual Brightness: How large and hot a star is in relation to other stars.

Which star looks like it is giving off more light?

• But, which star is actually giving off more light?

Hotter Stars

Cooler Stars

Luminous/Brighter Stars

Dim Stars

O B A F G K M

• Life Cycle of Stars Interactive Investigation http://aspire.cosmic-ray.org/labs/star_life/starlife_main.html

• HR Diagram Interacative Lab http://aspire.cosmic-ray.org/labs/star_life/hr_interactive.html

• Stellar Evolution/H-R Diagram Simulationhttp://instruct1.cit.cornell.edu/courses/astro101/java/evolve/evolve.htm

• Astronomy Place Tutorialshttp://media.pearsoncmg.com/bc/bc_bennett_cosmicpers_2/medialib/tutorials/index.html