10/3/14
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.
Brightness
brightest
darkest
hotter
cooler
Heat
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?
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.
False?
2 MINUTES TO DO THE T/F STATEMENTS
Statement
True?
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.
X
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.
False?
X–
White
Dwarf
X
X–
Red
Giant
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.