10/3/14

H-R Diagram

OBJECTIVES

• INTERPRET THE HERTZSPRUNG-RUSSELL DIAGRAM TO CLASSIFY STARS

• RECOGNIZE OUR SUN IS A MEDIUM-SIZED STAR

• CLASSIFY OUR SUN USING THE H-R DIAGRAM

• WHY?• IT HELPS US SEE HOW OUR GALAXY FITS INTO THE UNIVERSE

• HELPS US DETERMINE WHERE IN THE LIFE CYCLE A START IS

• PRACTICE READING GRAPHS AND CHARTS!

• TO SUCCEED ON THE COMMON ASSESSMENT, STAAR, AND TO REACH OUR GROWTH GOALS

KEY POINTS

• WE CAN CLASSIFY STARS BASED ON THEIR PROPERTIES OR CHARACTERISTICS.

• STARS CHANGE IN PROPERTIES AS THEY DEVELOP AND MOVE THROUGH THEIR LIFE CYCLE.

• THERE IS A RELATIONSHIP BETWEEN A STAR’S BRIGHTNESS (KNOWN AS LUMINOSITY OR MAGNITUDE) AND ITS TEMPERATURE.

H-R DIAGRAM

• THE HERTZSPRUNG-RUSSELL DIAGRAM IS A TOOL THAT SHOWS RELATIONSHIPS AND DIFFERENCES BETWEEN STARS BY COMPARING THEIR BRIGHTNESS AND TEMPERATURE

• IT SHOWS STARS OF DIFFERENT AGES AND IN DIFFERENT STAGES OF THE LIFE CYCLE OF A STAR, ALL AT THE SAME TIME.

• IT IS A GREAT TOOL TO CHECK YOUR UNDERSTANDING OF THE STAR LIFE CYCLE.

Heat

Brightness

coolerhotter

brightest

darkest

Each star is represented by a dot. The position of the dot tells us two things about the star: its brightness (luminosity) and its temperature.

WHICH HAS A HIGHER TEMPERATURE?

IN SOME VERSIONS OF THE HR DIAGRAM THE COLORS OF THE STARS ARE WRITTEN ACROSS IN THE ORDER OF: BLUE OR BLUE-WHITE, WHITE, YELLOW, RED-ORANGE, RED.

BLUE IS THE HOTTEST STAR AND RED IS THE COOLEST STAR. (JUST LIKE FIRE!)

WHICH HAS A HIGHER BRIGHTNESS?

2 MINUTES TO DO THE T/F STATEMENTS

Statement True? False?

A star with a luminosity of 0.01 solar units and a temperature of 40,000 Kelvin would be classified as a main sequence star.

   

Super giants are brighter than red giants.

   

White dwarfs are hotter and darker than a main-sequence star

   

A star with a brightness of 110 solar units and a temperature of 2700 Kelvin would be classified as a super giant.

   

Red giants have more luminosity than super giants.

   

2 MINUTES TO DO THE T/F STATEMENTS

Statement True? False?

A star with a luminosity of 0.01 solar units and a temperature of 40,000 Kelvin would be classified as a main sequence star.

   X – White Dwarf

Super giants are brighter than red giants.

 X  

White dwarfs are hotter and darker than a main-sequence star

 X  

A star with a brightness of 110 solar units and a temperature of 2700 Kelvin would be classified as a super giant.

   X – Red Giant

Red giants have more luminosity than super giants.

   X

AS A START GOES THROUGH THE LIFECYCLE.. IT MOVES AROUND THE HR DIAGRAM

http://aspire.cosmic-ray.org/Labs/StarLife/hr_interactive.html

PRACTICE JIGSAW

• YOU WILL WORK ON YOUR PRACTICE SECTION WITH THE OTHERS OF YOUR NUMBER, THEN HEAD BACK AND TEACH YOUR GROUP YOUR SECTION. WRITE YOUR ANSWERS TO THE QUESTIONS IN YOUR “THROUGH” SECTION FOR TODAY.