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CH. 4CH. 4Sec. 2 Sec. 2
Characteristics of StarsCharacteristics of Stars
constellationconstellation
• pattern of stars in sky
Orion the Hunter
Can you identify these constellations?
3.
1. 2.
4.
Cygnus the Swan
Pisces the FishGemini the Twins
Hydra the Snake
Main characteristics
Used to Classify
stars
main characteristics
used to classify
stars
Color Temp. size chemical composition
brightness
color & temp.color & temp.• star’s color tells its temp.• range from hottest coolest
–blue or blue-whitewhite red
Colors and Temperatures of Stars video clip
sizesize• smallest largest:1. neutron star
2. white dwarf star
3. medium-sized star
4. giant star
5.supergiant star
spectrographspectrograph
• breaks light into colors & produces image of resulting spectrum
• tells stars:
1. chemical composition
2. temperature
• amount of light given off• depends on size & temp.• described in 2 ways:
brightness
apparent brightnessbrightness as seen from Earth
absolute brightness brightness star would have if it were @
standard distance from Earth
The streetlights in this photo all give off about the same amount of light, and so have about the same absolute brightness.
light year• distance that light travels in 1 year
• = 9.5 million million (trillion) km
You and your friend are sitting behind a woman with a large hat. Why is your view of the screen different from your friend’s view?
Parallax at the Movies
parallaxparallax• method astronomers use to measure
distances to nearby stars
• apparent change in position of an object when you look @ it from different places
Why do nearby stars appear to change position between January and July?
• graph that shows relationship between
surface temp. & brightness
• most stars= main sequence- diagonal line
in ctr. of graph
Hertzsprung-Russell Diagram
The constellation, Orion includes the red supergiant Betelgeuse, the blue supergiant Rigel, and many other main sequence and giant stars.