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Insert: Beyond our Solar System

This overview delves into the deployment of the Hubble Space Telescope in 1990, revealing insights into stellar evolution, including the Hertzsprung-Russell diagram that maps the relationship between stellar brightness and temperature. Key stages of stellar life cycles such as birth, main-sequence, red giant, and death—including phenomena like supernovae, neutron stars, and black holes—are explored. Additionally, we discuss various galaxy types and the Doppler effect, which provides evidence of an expanding universe post-Big Bang, linking cosmic observations to the fate of the universe.

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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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