Life Cycle Of A Star


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The life and death of a star as needed to know by a 6th grader

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  • Forms a protostar (1 st stage of a star) The first type of nebulae we are going to explore are called Emission Nebulae, because they emit their own light. Red or pink. A blue relfection nebulae is completely different from an emission nebulae.  This is because rather than emitting their own light, they are reflecting the light of the stars around them Although this third type of nebulae is called a planetary nebulae, it actually has nothing to do with planets.  A planetary nebulae is formed when a dying sun sized star begins to shed its outer layers.
  • Gravity pulls the dust and gas into a sphere. As it gets hotter and denser the gases change from Hydrogen to helium and called nuclear fusion
  • A star can change classifications as it gets older
  • Huge amount of energy in the core and releases lots of energy (hydrogen to fuse the helium atoms) This is the stage our sun is currently in!
  • Without hydrogen, gravity wins and causes the star to contract. Stars core temp increases and shell temp decreases Hydrogen loss causes the center of the star to shrink and the atmosphere of the star grows very large and cools to form a red giant or a supergiant. Red giants can be 10 times bigger than the sun and supergiants are 100 times bigger.
  • No hydrogen left and can’t generate energy by fusion. Can shine for billion of years before they cool Leaves a really hot core. Hot in temperature, but not very bright because it is smaller in size now Can die and become a black dwarf or explode into a nova. The whole process then may be repeated! Or it could supernova and become a neutron star which may turn into a black hole
  • Hertzsprung compared the brightness and temperature of a stars on a graph. Two years later Norris made similar graphs.
  • Shows how stars are classified and how they change over time
  • Modern HR diagram. Temperature is on bottom and luminosity (or absolute magnitude) is on the left side. Hot stars are (blue) on the left and do not stay in main sequence very long. Quickly use up they hydrogen in their cores. Cool stars (red) are on the right. Red stars are low mass stars and remain there a long times and are the oldest stars. Bright stars are at the top and dim stars are at the bottom. The brighteset stars on here are 1 million times brighter than the sun. The dimmest are 1/10,000 as bright as the sun. The diagonal pattern you see is the Main Sequence. This is where the star spends the majority of its life. As they age from the main sequence, they move up and to the righ on the Hr diagram to become giants or supergiants and then down to the left to become white dwarfs. Point out the sun. It is an average star and is in the main sequence.
  • Remember, the lower the magnitude, the brighter the star
  • Produce hydrogen fasters than the stars like the sun do. Generate more energy which makes them blue. Explosion is so fierce it may light up the entire galaxy for several days.
  • After a supernova explodes the materials in the center are squeezed together to form a new star. This is two times bigger than the sun. The particles inside lose their charge and become neutrons. If it is spinning it is called a pulsar. Pulsar sends out beams of radiation. Detected by radio telescopes as clicks, or pulses.
  • Shows you the star during its explosion on the right, and on the left before its explosion. Picture on the right was taken by the Hubble in 1994. the stars remains form a double ring of gas and dust.
  • This was the first supernova visible to the unaided eye in 400 years.
  • Doesn’t gobble up stars like shown in the movies. However, they don’t give off light so locating them can be difficult. If a star is nearby, some gas or dust from the star will spiral into the black hole and give off X rays. These x rays are we how detect black holes.
  • Life Cycle Of A Star

    1. 1. Science Daily Starter April 27, 2008 <ul><li>Label page </li></ul><ul><ul><li>Creative Writing </li></ul></ul><ul><li>Label page </li></ul><ul><ul><li>Daily Starters April 28-May 2 </li></ul></ul><ul><ul><li>Your daily starter is to come….. </li></ul></ul>
    2. 2. Science Daily Starter April 27, 2008 <ul><li>What is the first stage in the life cycle of a star? </li></ul>
    3. 3. Life Cycle of a Star Ms. Hyche 1 st , 2 nd , 6 th period Science
    4. 4. Nebulae <ul><li>Nebulae </li></ul><ul><ul><li>A nebulae is a cloud of gas and dust in outer space.  </li></ul></ul><ul><ul><li>These clouds are often very large, spanning across many light years.  </li></ul></ul><ul><ul><li>There are many different kind of nebulas in the sky </li></ul></ul>
    5. 5. Nebulaes <ul><li>Ring Nebulae </li></ul><ul><li>Double Lobed Nebulae </li></ul>
    6. 6. Other Nebulaes…. <ul><li> </li></ul>
    7. 7. Life Cycle of Stars <ul><li>Just like people, stars are born, grow old, and eventually die. </li></ul><ul><li>The difference is, stars exist for billions of years. </li></ul>
    8. 8. How do stars form? <ul><li>They are born when clouds of gas and dust come together and become very hot and dense. (nuclear fusion) </li></ul><ul><li>As stars get older, they lose some of their material. </li></ul><ul><li>Usually this is a gradual change, but sometimes it happens in a big explosion. </li></ul><ul><li>Either way, when a star dies, much of its material returns to space. </li></ul><ul><li>There some of it combines with more gas and dust to form new stars. </li></ul>
    9. 9. Types of Stars <ul><li>Determinded by size, mass, brightness, color, temperature, specturm, and age </li></ul><ul><li>Main-sequence stars, giants, supergiants, white dwarfs </li></ul>
    10. 10. Main-Sequence Stars <ul><li>Second and longest stage </li></ul><ul><li>Energy generated in the core, and released </li></ul><ul><li>Size changes very little as long as there is a continuous supply of hydrogen atoms to fuse the helium atoms </li></ul>
    11. 11. Giants and Supergiants <ul><li>Third stage </li></ul><ul><li>Star can become a red giant </li></ul><ul><ul><li>A star that expands and cools once it uses its hydrogen </li></ul></ul><ul><ul><li>Star will shrink </li></ul></ul>
    12. 12. Scale
    13. 13. White Dwarfs <ul><li>Final stage </li></ul><ul><li>Size of the sun or smaller </li></ul><ul><li>White Dwarf </li></ul><ul><ul><li>Small, hot star that is the leftover center of an older star </li></ul></ul>
    14. 14. The Diagram That Did It! <ul><li>In 1911, a Danish astronomer named Ejnar Hertzsprung compared the temperature and brightness of stars on a graph. </li></ul><ul><li>Two years later, American astronomer Henry Norris Russell made some similar graphs. </li></ul>
    15. 17. The Diagram That Did It <ul><li>Although they used different data, they had similar results. </li></ul><ul><li>The combination of their ideas is now called the Hertzsprung-Russell, or H-R diagram . </li></ul><ul><ul><li>The H-R diagram is a graph showing the relationship between a star’s surface temperature and its absolute magnitude. </li></ul></ul>
    16. 20. Continued <ul><li>The H-R-diagram has become a tool for studying the nature of stars. </li></ul><ul><li>It shows how stars are classified by temperature and brightness AND it’s a good way to illustrate how stars change over time. </li></ul>
    17. 21. As stars age…. <ul><li>Average stars (sun), become red giants and then white dwarfs </li></ul><ul><li>More massive stars may explode with such intensity that they become strange objects such as supernovas, neutron stars, pulsars, and black holes </li></ul>
    18. 22. Supernovas <ul><li>Massive blue stars with short lives </li></ul><ul><li>Supernova </li></ul><ul><ul><li>Gigantic explosion in which a massive star collapses. </li></ul></ul>
    19. 23. Neutron Stars <ul><li>Neutron star </li></ul><ul><ul><li>A star that has collapsed under gravity to the point that the electrons and protons have smashed together to form neutrons </li></ul></ul><ul><li>Pulsar </li></ul><ul><ul><li>Spinning neutron star </li></ul></ul>
    20. 24. 1987A
    21. 25. 1987A
    22. 26. Blackholes <ul><li>Leftovers of a supernova that they collapse </li></ul><ul><li>Black hole </li></ul><ul><ul><li>Object so massive and dense that even light can’t escape its gravity </li></ul></ul>
    23. 28. Life Cycles <ul><li>The life cycle of a star varies, depending on the mass of the star. </li></ul><ul><li>Higher mass stars develop more quickly than lower mass stars. Toward the end of their life, they also behave differently. </li></ul>
    24. 29. More on life cycles <ul><li>Stars form inside a cloud of gas and dust called a nebula. </li></ul><ul><li>Gravity pulls gas and dust closer together in some regions of a nebula. </li></ul><ul><li>As the matter contracts, it forms a hot, dense sphere. </li></ul><ul><li>The sphere becomes a star if the center grows hot and dense enough for fusion to occur. </li></ul>
    25. 37. Death of a Star <ul><li>When a star begins to run out of fuel, its core shrinks and its outer portion expands. </li></ul><ul><li>Depending on its mass the star becomes either a red giant or a supergiant. </li></ul><ul><li>These evolve in very different ways. </li></ul>
    26. 38. Low or Medium Mass Star <ul><li>Low or medium mass star </li></ul><ul><ul><li>Red Giant </li></ul></ul><ul><ul><li>Planetary Nebula </li></ul></ul><ul><ul><li>White Dwarf </li></ul></ul><ul><ul><li>Black Dwarf </li></ul></ul>
    27. 39. High Mass Star <ul><li>High Mass Star </li></ul><ul><ul><li>Supergiant </li></ul></ul><ul><ul><li>Supernova </li></ul></ul><ul><ul><li>Black hole (gravity so strong that nothing, not even light, can escape) or neutron star </li></ul></ul>
    28. 40. In conclusion…. <ul><li>Nebulae </li></ul><ul><li>Main-Sequence Star </li></ul><ul><li>Giants or Red Giants </li></ul><ul><li>White Dwarfs </li></ul><ul><li>Supernovas, Neutrons, Blackholes </li></ul>