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III. Lives of Stars. A. Studying the Lives of Stars. Not really alive Cannot watch a single star for billions of years so they observe many stars and see how they differ from one another. B. A Star is Born. Nebula- large amount of gas and dust spread out in an immense volume
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A. Studying the Lives of Stars • Not really alive • Cannot watch a single star for billions of years so they observe many stars and see how they differ from one another
B. A Star is Born • Nebula- large amount of gas and dust spread out in an immense volume • All stars begin as parts of nebulas • Gravity pulls the gas and dust together • Prostar- earliest stage of a stars life • A star is born when nuclear fusion occurs
C. Lifetimes of Stars • How long a star lives depends on how much mass it has • Small mass stars use up their fuel more slowly than large mass stars so they live longer
D. Deaths of Stars • When a star runs our of fuel it starts to expand and is considered to be a red giant • It can be a white dwarf, neutron star or a black hole • White Dwarf- blue-white core is left behind • Size of Earth • Glows from leftover energy-when dead called a black dwarf
Neutron Stars • Dying super giant explosion • Some material from the star is left behind • Forms neutron star • Smaller and denser than white dwarfs
Black holes- most massive stars become when they die • Gravity is so strong that it pulls everything inward • Nothing can escape not even light • No radiation can get out of the black hole
Quasars- distant galaxies • Very bright but very far away • Giant black holes at the center • The gas heats up and shines brightly