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Components of the Universe

Components of the Universe. Chapter 11 . 11.1 STARS . Stars are spherical objects in space that radiate energy from their hot cores like a thermonuclear reactor. They outnumber all other celestial bodies. Stars have a life span like all living things on earth.

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Components of the Universe

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  1. Components of the Universe Chapter 11

  2. 11.1 STARS • Starsarespherical objects in space that radiate energy from their hot cores like a thermonuclear reactor. • Theyoutnumber all other celestial bodies. • Starshave a life spanlike all living things on earth. • How long a star lives for depends on its mass.

  3. Carl Sagan, an American writer and astronaut, once said “there are more stars in the Universe than grains of sand on all the beaches on the earth.” Space is not empty, but filled with interstellar matter which is made up of gas (mainly hydrogen) and dust. • Even though only 1% of all interstellar matter is dust , it is the dust that makes it hard for astronomers to see light from distant stars.

  4. The Birth of a Star • Stars begin to form from the materials in a NEBULA, when gravity starts acting on chunks of gas and dust. The mass grows until it finally collapsesin on itself. • An early phase of star, called a protostar, is created. • If the protostar collects enough dust and gas, its core will reach 10 000 000 ºC and the atoms start to fuse together.

  5. The Birth of a Star • The process of hydrogen atoms joining to form helium atoms is called nuclear fusion. • Nuclear fusion creates an enormous amount of energy. • It is the energy given off by fusion that causes stars to glow.

  6. The Evolution of STARS Similar to all living things, stars age. Theyall start in a NEBULA,but the path of development differs depending on the mass of the newborn star. The three paths are; • Low Mass Stars • Intermediate Mass Stars • High Mass Stars

  7. Low Mass Stars • These stars start out small and remain that way for most of their life as dim to cool red dwarfs.Red dwarfs burn their hydrogen at a much slower rate and may last for 100 billion years.

  8. Intermediate Mass Stars • These stars are similar in mass to our Sun. They burn their hydrogenfasterthan low mass stars. They last about 10 billion years. • They will eventually expand into a red giant, then they collapse into a small, dim white dwarf. As it cools, it turns into a black dwarf, a dense, dark body of mostly carbon and oxygen.

  9. High Mass Stars • These stars have 12 times the massof our Sun. They expand and burn their gases rapidlybecoming red giants. Their life span is about 7 billion years. • They have a violent ending collapsing onto themselves with a massive explosion called a supernova.When these supernovas explode they send heavy elements into space. The carbon, oxygen, and hydrogen we use on earth comes from these supernovas exploding.

  10. BLACK HOLES • When a star more than 25 times more massive than our Sun explodes into a supernova, it becomes a black hole and collapses into itself. • Because the material is so dense and has an extraordinary amount of gravitational pull, nothing can escape its force, not even light.

  11. BLACK HOLES • Proofthat black holes exist: a) material pulled toward the center of black holes will emit radiation b) gravity from black holes affects passing stars and galaxies c) models show how super-dense objects can distort light from stars

  12. STAR SIZES • Many stars visible from Earth are much larger that our Sun.

  13. AnalyzingSTAR COLOURS • Two things can be determined about stars when looking at them through powerful telescopes. • The stars colour reveals; A) temperatureandcomposition B) whether the star is moving away from earth or toward earth

  14. Colour and Temperature • RED starsare cool3000oC • YELLOWstarsare hot6000oC • BLUEstars are hottest20,000oC-35,000oC

  15. Colour and Composition Spectroscopes are used to analyze chemical composition.Using a spectroscope, the light emitting from a star reveals spectral bands that show certain gases in the star.

  16. Colour and Motion Scientists use something called the “Doppler Effect” which measures changes in wavelength because of motion. Changes in sound waves can also be detected. When waves are analyzed it shows whether the pattern of light is being compressed or extended. If a star is coming closer toward Earth, the wavelengths of light become compressed. Section 11.1 Quiz

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