Download STARS- hot glowing sphere of gas that produces energy by

STAR- hot glowing sphere of gas that produces energy by fusion
1] Light year—distance light travels in a year (9.5 trillion km, 6 trillion miles)
2] Star brightness
A) Actual brightness- brightness right next to a star
B) Apparent brightness—brightness as seen from earth
3] Formation of stars
A) Nebula (cloud of dust and gas) collapses under its own gravity
B) Friction in core causes temperature to reach 10,000,000 c
C) fusion begins and a star is born
4] How stars are found
A) Loner-by itself (our sun)
B) Binary system- 2 stars orbiting each other
C) Star cluster- 100’s or 1000’s of stars held together by gravity (naked eye sees this as
1 point of light)
5] Star composition
A) Dark line spectrum analysis- compare a star’s spectrum to an element’s spectrum
(its fingerprint)
6] Star temperature
A) 3500 degrees c= red
B) 5500 degrees c= orange
C) 7500 degrees c=yellow
D) 9500 degrees c= blue
E) 11,000 degrees c= white
7] Hertzsprung-Russell diagram –see handout
A) Star life
1) Red dwarf- lasts trillions of years (small car- small tank but great gas milage)
2) Sun class-last billions of years (mid sized car- medium tank, medium milage
3) Blue giant- millions of years (gas gusler- huge tank of fuel, but uses it up very
quickly)
B) Star death
1) Red dwarf- swell into red giant then shrink into a white dwarf
2) Sun class- swell into red giant then shrink into a white dwarf
3) Blue giant- swell into super giant then
a) Small ones explode into a super nova (new
nebula)
b) Large ones shrink into a black hole
8] Forces in stars
A) Fusion pushes out
B) Gravity pulls in
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When forces are balanced star is “living”
When mass decreases there is less gravity,
thus fusion expands it
When fusion slows down, gravity forces
start to win again and shrink the star