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Life Cycle Of Stars
- 1. Life Cycle ofa Star
- 2. All Stars Beginthe Same Way: Before life as a star Nebula A nebula is a cloud of interstellar dust, hydrogen and helium gas, and plasma
- 3. All Stars Beginthe Same Way: 1 st Stage of Life – the Protostar Ball of gas and dust that is pulled together by gravity Nuclear fusion starts as gas cloud becomes denser and hotter Nuclear Fusion hydrogen atoms fuse into helium Creates the intense energy found in stars
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- 6. The Life CycleDepends on Starting Mass Protostar Main Sequence White Dwarf Black Dwarf Protostar Main Sequence Red Giant White Dwarf Black Dwarf Protostar Main Sequence Super Giant Supernova neutron star black hole Small Mass Medium Mass Large Mass
- 7. Main Sequence Stagelongest stage hydrogen fuses into helium which creates enormous amounts of energy (nuclear fusion) the size of the star does not change much this is the stage our sun is currently in “ middle age”
- 8. Main Sequence StageRemember, all stars go through a main sequence stage Large Mass stars = large main sequence stars Medium Mass stars = medium-sized main sequence stars
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- 10. Red Giants ThisStage Happens for Medium Mass Stars Only occurs when star begins running out of hydrogen – it starts cooling and expanding at the same time center shrinks and atmosphere swells
- 11. Red Giants theend of the red giant stage occurs when the atmosphere of the star becomes so spread out it slowly dissipates this stage is called “planetary nebula”
- 12. Red Giants planetarynebula white dwarf
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- 14. White Dwarfs WhiteDwarf small hot star that is the leftover center of an older star Can shine for billions of years before they extinguish
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- 17. Supergiants Stage ThatHappens For Large Mass stars only occurs when star begins running out of hydrogen – it starts cooling and expanding at the same time center shrinks and atmosphere swells looks a lot like a red giant, doesn’t it?
- 18. Supergiants the bigdifference is the size and brightness supergiants are up to 1,000,000 times brighter than the sun medium star Jupiter large mass star
- 19. Relative Size ofStars Giant stars
- 20. Supernova Supernova gigantic explosion in which a massive star collapses occurs after a massive star uses up its fuel source supernova
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- 22. Neutron Star Neutron Star A neutron star that spins and sends out beams of radiation is called a pulsar a star that has collapsed to a point at which all particles are neutrons
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- 24. Black Hole BlackHole an object that is so massive that light cannot escape its gravity Astronomers can detect black holes by using X-ray telescopes
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- 26. Neutron Star orBlack Hole? Black Hole Neutron Star ~ 8 to 15 solar masses > 15 solar masses
- 27. Summary Observe lifeof a star Recall: Comprehend: Apply: S T A R S S T T A A R R
- 28. What is thelongest stage for any star? All stars remain in their Main Sequence stage longer than in any other stage
- 29. What are neutronstars made of? Neutron stars are made of neutrons . A neutron star is so dense that a teaspoonful would weigh 1 billion tons!
- 30. What kind ofstars form a supernova? Only large mass stars form supernova.
- 31. What kind ofstars form red giants? Medium mass stars like our sun form red giants.
- 32. What size ofstars will form black holes? Only stars with 15 solar masses or larger will form black holes.
- 33. What kind ofstars “skip” the red giant /supergiant phase altogether? Small mass stars go straight from their main sequence stage to white dwarf
- 34. What stages doall stars have in common? All stars begin as nebula , become protostars and then become main sequence stars.
- 35. What kind ofstars are smaller than Earth? Both white dwarfs and neutron stars are smaller than Earth.
- 36. What is theone factor that determines the ultimate fate of a star? The mass of a star determines its fate.
- 37. Which main sequencestars are larger than the Earth? All main sequence stars are larger than Earth.
- 38. Why won’t oursun ever become a black hole? Our sun will never become a black hole because it does not have enough mass .
- 39. How many timeslarger would our sun have to be to supernova? It takes a star that is at least 8 solar masses to be massive enough to supernova, so our sun would have to be at least 8 times as large.