Star Formations and Life Cycles


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Star Formations and Life Cycles

  1. 1. By Carla Bridges
  2. 2.  5.3.2 Observe and describe that stars are like the sun, some being smaller some being larger, but they are so far away that they look like points of light.  5.3.3 Observe the stars and identify stars that are unusually bright and those that have unusual colors, such as reddish or bluish.  Language Arts:  5.2.1 Structural Features of Informational and Technical Materials: Use the features of informational texts, such as formats, graphics, diagrams, illustrations, charts, maps, and organization, to find information and support understanding. (Core Standard)
  3. 3.  Click on this icon to go to Table of contents.  Click on this icon for picture of star on that page.  Click on this icon for narration.  Click high-lighted words for more information.
  4. 4.  Star Formations  Types of Stars  Colors of Stars  Temperature of Stars  Life Cycle of Stars  Vocabulary  Resources
  5. 5.  Stars form from collapsing clouds of gas and dust.  As the cloud collapses, its density and temperature increase.  The temperature and density are highest at the center of the cloud, where a new star will eventually form.  A protostar is the beginning stage of a star.  Stars will either form into low mass stars or high mass stars.
  6. 6. Birth of a Star  The type of star formed depends on what type of fusion happens.  Click here for more information on high-mass and low-mass stars.  High-mass and low mass stars have different life cycles.  High-mass stars evolve quicker and go supernovae.  Low mass stars turn into white dwarfs.
  7. 7. A protostar is what you have before a star forms. A protostar is a collection of gas that has collapsed down from a giant molecular cloud. The protostar phase of stellar evolution lasts about 100,000 years. Over time, gravity and pressure increase, forcing the protostar to collapse down. All of the energy release by the protostar comes only from the heating caused by the gravitational energy – nuclear fusion reactions haven't started
  8. 8.  A T Tauri star is a stage in a star's formation and evolution right before it becomes a main sequence star. This phase occurs at the end of the protostar phase, when the gravitational pressure holding the star together is the source of all its energy. T Tauri stars don't have enough pressure and temperature at their cores to generate nuclear fusion, but they do resemble main sequence stars; they're about the same temperature but brighter because they're a larger. T Tauri stars can have large areas of sunspot coverage, and have intense X-ray flares and extremely powerful stellar winds. Stars will remain in the T Tauri stage for about 100 million years.
  9. 9. A star in the main sequence is in a state of hydrostatic equilibrium. Gravity is pulling the star inward, and the light pressure from all the fusion reactions in the star are pushing outward. The inward and outward forces balance one another out, and the star maintains a spherical shape. Stars in the main sequence will have a size that depends on their mass, which defines the amount of gravity pulling them inward
  10. 10.  When a star has consumed its stock of hydrogen in its core, fusion stops and the star no longer generates an outward pressure to counteract the inward pressure pulling it together. A shell of hydrogen around the core ignites continuing the life of the star, but causes it to increase in size dramatically. The aging star has become a red giant star, and can be 100 times larger than it was in its main sequence phase. When this hydrogen fuel is used up, further shells of helium and even heavier elements can be consumed in fusion reactions. The red giant phase of a star's life will only last a few hundred million years before it runs out of fuel completely and becomes a white dwarf.
  11. 11.  When a star has completely run out of hydrogen fuel in its core and it lacks the mass to force higher elements into fusion reaction, it becomes a white dwarf star. The outward light pressure from the fusion reaction stops and the star collapses inward under its own gravity. A white dwarf shines because it was a hot star once, but there's no fusion reactions happening any more. A white dwarf will just cool down until it because the background temperature of the Universe. This process will take hundreds of billions of years, so no white dwarfs have actually cooled down that far yet.
  12. 12.  Red dwarf stars are the most common kind of stars in the Universe. These are main sequence stars but they have such low mass that they're much cooler than stars like our Sun. They have another advantage. Red dwarf stars are able to keep the hydrogen fuel mixing into their core, and so they can conserve their fuel for much longer than other stars. Astronomers estimate that some red dwarf stars will burn for up to 10 trillion years. The smallest red dwarfs are 0.075 times the mass of the Sun, and they can have a mass of up to half of the Sun.
  13. 13.  Ifa star has between 1.35 and 2.1 times the mass of the Sun, it doesn't form a white dwarf when it dies. Instead, the star dies in a catastrophic supernova explosion, and the remaining core becomes a neutron star. As its name implies, a neutron star is an exotic type of star that is composed entirely of neutrons. This is because the intense gravity of the neutron star crushes protons and electrons together to form neutrons. If stars are even more massive, they will become black holes instead of neutron stars after the supernova goes
  14. 14.  The largest stars in the UniverseThe largest stars in the Universe are supergiant stars. These are monsters with dozens of times the mass of the Sun. Unlike a relatively stable star like the Sun, supergiants are consuming hydrogen fuel at an enormous rate and will consume all the fuel in their cores within just a few million years. Supergiant stars live fast and die young, detonating as supernovae; completely disintegrating themselves in the process are supergiant stars.
  15. 15.  Greenish  Blue  White  Whitish-yellow  Yellow  Yellowish-orange  Orange  Orange-red  Red
  16. 16. Color Temperature Blue Over ~ 25,000 K White ~7,000 K Yellow ~6,000 K Orange ~5,000 K Red ~Under 3,500 K
  17. 17.  Celestial object- natural object in the sky  Solar mass- the unit, equivalent to the mass of the sun, in which the masses of stars and other celestial objects are given  Solar unit- the unit, equivalent to the length between the Earth and the Sun: 93 million miles or 150 million kilometers  Stellar evolution- the lives of stars  Stellar wind- flow of neutral or charged gas ejected from the upper atmosphere of a star.
  18. 18.  X-ray flares- happens when energy stored in twisted magnetic fields (usually above sunspots) is suddenly released. Flares produce a burst of radiation across the electromagnetic spectrum, from radio waves to x-rays and gamma-rays.  Sunspots- Any of the relatively cool dark spots appearing periodically in groups on the surface of the sun that are associated with strong magnetic fields.  Planetary nebula-forms when a star can no longer support itself by fusion reactions in its center. The gravity from the material in the outer part of the star takes its inevitable toll on the structure of the star, and forces the inner parts to condense and heat up
  19. 19.  /types.htm  space/stars/types-of-stars/  u/kstars/ai-colorandtemp.html  ior/astrophysics/photometry_colour.html  /sform.html
  20. 20.  f+stars&*:IE- SearchBox&oe=UTF- 8&sourceid=ie7&rlz=1I7GGLL_en&um=1&ie=U TF- 8&ei=dqzfSrp_jZowqZjEwwg&sa=X&oi=image _result_group&ct=title&resnum=4&ved=0CCM QsAQwAw 