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Insert: Beyond our Solar System

Insert: Beyond our Solar System. Deployment of the Hubble Space Telescope in Earth orbit, April 24, 1990. The 300-meter radio telescope at Arecibo, Puerto Rico. Hertzsprung-Russell diagram. Shows the relation between stellar Brightness (absolute magnitude) and Temperature

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Insert: Beyond our Solar System

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  1. Insert:Beyond our Solar System

  2. Deployment of the Hubble Space Telescope in Earth orbit, April 24, 1990

  3. The 300-meter radio telescope at Arecibo, Puerto Rico

  4. Hertzsprung-Russell diagram • Shows the relation between stellar • Brightness (absolute magnitude) and • Temperature • Diagram is made by plotting (graphing) each star's • Luminosity (brightness) and • Temperature

  5. Hertzsprung-Russell diagram • Parts of an H-R diagram • Main-sequence stars • 90% of all stars • Band through the center of the H-R diagram • Sun is in the main-sequence • Giants (or red giants) • Very luminous • Large • Very large giants are called supergiants • Only a few percent of all stars

  6. Hertzsprung-Russell diagram • Parts of an H-R diagram • White dwarfs • Fainter than main-sequence stars • Small (approximate the size of Earth) • Lower-central area on the H-R diagram • Not all are white in color • Perhaps 10% of all stars

  7. Hertzsprung-Russell diagram

  8. The Orion Nebula is a well-known emission nebula

  9. A faint blue reflection nebula in the Pleiades star cluster

  10. Stellar evolution • Two opposing forces in a star are • Gravity – contracts • Thermal nuclear energy – expands • Stages • Birth • Main-sequence stage • 90% of a star's life is in the main-sequence • Red giant stage • Burnout and death • white dwarf, neutron star, or a black hole

  11. Evolutionary stages

  12. Stellar evolution

  13. Stellar remnants • White dwarf • Small and Dense • Spoonful weighs several tons • Neutron star • Gravitational force collapses atoms • Electrons combine with protons to produce neutrons • Pea size sample weighs 100 million tons • First one discovered in early 1970s Crab nebula (remnant of an A.D. 1054 supernova)

  14. Crab Nebula in the constellation Taurus

  15. Stellar remnants • Black hole • More dense than a neutron star • Intense surface gravity lets no light escape • As matter is pulled into it • Becomes very hot • Emits x-rays • Likely candidate is Cygnus X-1, a strong x-ray source

  16. Binary Pair with a Red Giant and a Black Hole

  17. Galaxies • Other galaxies • Existence was first proposed in mid-1700s by Immanuel Kant • Four basic types of galaxies • Spiral galaxy • Arms extending from nucleus • About 30% of all galaxies • e.g., Milky Way

  18. Face-on view of the Milk Way Galaxy

  19. Edge-on view of the Milk Way Galaxy

  20. Great Galaxy, a spiral galaxy, in the constellation Andromeda

  21. Galaxies • Other galaxies • Four basic types of galaxies • Barred spiral galaxy • Elliptical galaxy • Irregular galaxy

  22. The study of light • Doppler effect • The apparent change in wavelength of radiation caused by the relative motions of the source and observer • Used to determine • Direction of motion • Increasing distance – wavelength is longer ("stretches") • Decreasing distance – makes wavelength shorter ("compresses")

  23. The Doppler effect

  24. Red shifts • Doppler effect • Change in the wavelength of light emitted by an object due to its motion • Movement away stretches the wavelength • Light appears redder • Movement toward “squeezes” the wavelength • Light shifted toward the blue • Expanding universe • Most galaxies exhibit a red Doppler shift

  25. Raisin bread analogy of an expanding universe

  26. Big Bang theory • Accounts for galaxies moving away from us • Universe was once confined to a "ball" that was • Supermassive • Dense • Hot

  27. Big Bang theory • Big Bang marks the inception of the universe • Occurred about 15 billion years ago • All matter and space was created • Matter is moving outward • Fate of the universe • Two possibilities • Universe will last forever • Outward expansion sill stop and gravitational; contraction will follow

  28. Big Bang theory • Fate of the universe • Final fate depends on the average density of the universe • If the density is more than the critical density, then the universe would contract • Current estimates point to less then the critical density and predict an ever-expanding, or open, universe

  29. End of Chapter 16

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