Earth science 25.2

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Earth science 25.2

  1. 1. 25.2 Stellar Evolution<br />
  2. 2. Protostar<br />A collapsing cloud of gas and dust destined to become a star; a developing star not yet hot enough to engage in nuclear fusion.<br />
  3. 3. Supernova<br />An exploding star that increases in brightness many thousands of times.<br />
  4. 4. White Dwarf <br />A star that has exhausted most or all of its nuclear fuel and has collapsed to a very small size, believed to be near its final stage of evolution.<br />
  5. 5. Neutron Star<br />A star of extremely high density composed entirely of neutrons.<br />
  6. 6. Pulsar <br />A variable radio source of small size that emits radio pulses in very regular periods.<br />
  7. 7. Black Hole <br />A massive star that has collapsed to such a small volume that its gravity prevents the escape of everything, including light.<br />
  8. 8. Key Concept<br />When the core of a protostar has reached about 10 million K, pressure within is so great that nuclear fusion of hydrogen begins, and a star is born.<br />
  9. 9. Key Concept<br />We do know all stars, regardless of their size, eventually run out of fuel and collapse due to gravity.<br />
  10. 10. Key Concept<br />As you can see, the sun begins as a nebula, spends much of its life as a main-sequence star, becomes a red giant, planetary nebula, white dwarf, and finally, black dwarfs.<br />

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