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STARS

Explore the fascinating world of stars, their colors determined by surface temperature, and their incredible life cycles from nebulae to supernovae. Discover how optical telescopes and radio satellites collect and analyze light and radio waves from these massive celestial bodies. Learn about key concepts like electromagnetic spectrum, Doppler effect, and the HR diagram while diving into the classification of stars and galaxies. This comprehensive overview will enhance your understanding of the universe and the stellar phenomena within it.

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STARS

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  1. STARS • BALL OF GASES, MOSTLY HYDROGEN AND HELIUM • Are all stars the same color? • NO! • Color- determined by surface temperature.

  2. 1. Blue- young and hottest • Ex. Rigel (above 30,000 degrees Celsius • 2. White - usually old and hot Ex. Sirius (10,000 oC) 3. Yellow – Average (5000-6000oC ) temperature and middle age • Ex. The sun

  3. 4 – Red- coolest and growing old • Ex. Betelgeuse less than 3,500oC

  4. All radiant energy that travels the speed of light in waves Ultraviolet ^ Infrared shortest longest Electromagnetic Spectrum

  5. Longest to shortest wavelength

  6. Spectroscope • Attaches to an optical telescope • Analyzes light from the stars Bright line spectrum

  7. Separates visible light by its different wavelengths • Each element is then identified by its own spectrum • Shows direction, movement and composition Spectrum___

  8. DOPPLER EFFECT **THE APPARENT SHIFT IN WAVELENGTH DUE TO A MOVING OBJECT Red shift- moving away Blue shift- moving toward

  9. DISTANCE LIGHT TRAVELS IN ONE YEAR • 6,000,000,000,000 MILES (186,000 mi/sec) or • 300,000 km/s • AU: Astronomical unit • Distance from Earth to Sun • 149,597,870,700 m or just 1 AU

  10. Distance is measured by using PARALLAX- • THE APPARENT SHIFT IN MOTION over time • Ex. • Hold out one arm and give a thumbs up • Close one eye and cover the Red Star • Now switch eyes • That apparent change is parallax!

  11. 2. Apparent Brightness (Magnitude) • A. The brightness we see from earth • B. Depends on size, distance and surface temperature.

  12. C. Star’s Brightness • 1. Luminosity or absolute magnitude. • A. Actual brightness of the star • B. found by using the distance and apparent magnitude.

  13. OPTICAL TELESCOPES 1. REFRACTING TELESCOPE **uses lenses to bend light to a focus point person

  14. 2. Reflecting Telescope • Uses mirrors • Concave mirror reflects light to a flat mirror • Ex. Hubble Space Telescope • Hale telescope

  15. 3. Catadioptric Telescope • Uses mirrors • AND Lenses • Ex. Celestron 8

  16. Problems with Optical telescopes • Light pollution

  17. EM (electromagnetic) spectrum

  18. Jansky 1905-1950 • Discovered radio waves in space 1931

  19. Reber- 1911-2002 • Built the first radio telescope (1937) Collects radio waves from space Can be used at anytime or weather

  20. VLA in New Mexico

  21. ASTRONOMICAL INSTRUMENTS

  22. Radio Telescopes • Operate in the radio frequency portion of the EM spectrum where they can detect and collect data on radio sources. • Used anytime, no light pollution or weather problems

  23. Scientific Terms a (testable) proposed explanation for a phenomenon a well-confirmed type of explanation of nature, made in a way consistent with scientific method describes some aspects of the universe or phenomenon Alvarez hypothesis “Meteor-impact” "Big Bang theory" “gravity”

  24. D. Classification • 1. H. R. diagram (Hertzsprung – Russell) • 2. Classifies by surface temperature and absolute magnitude. • 3. Main sequence stars- stars of similar composition and size • A. “average” stars

  25. 4. Outside of main sequence • A. Red super giants and red giants • B. Blue Giants. • C. White Dwarfs Betelgeuse

  26. Rigel Betelgeuse Sun Sirius

  27. E. Life Cycle Of Stars • STEP 1. Begins as a nebula- a cloud of dust and gas. (mostly H and He)

  28. STEP 2.Protostar- gravity forms a ball-shaped pocket and temperature increases.

  29. STEP 3. Nuclear fusion • 4 hydrogen fuse to make helium plus energy • Occurs in the core • Must be 10 mil • degrees C

  30. STEP 4. Main Sequence Star • Must have enough mass to have nuclear fusion for its energy

  31. STEP 5. RED GIANTS • Size of giants depends on the initial mass • Could be a super red giant like Betelgeuse • No more H(very little), He turns into C More energy HHe and HeC, gravity cant hold on ahhh!

  32. STEP 6. Supernova or white dwarf • a) white dwarf- small, hot, older star no shell, only core left to cool • 1. Ex. Sirius or the Sun (some day) • b) supernova- gigantic explosion of a large mass star like Betelgeuse • Chinese recorded one in 1054 AD

  33. Supernova Feb.24, 1987 170,000LY

  34. NEUTRON STAR 1. Extremely dense; like the mass of our sun into a 8 mi diameter

  35. d) Black hole- • 1. An object so dense that not even light can escape its surface

  36. Quasars- Very powerful source of energy most distant objects in space • Pulsars- • a neutron star that spins rapidly and sends out radio waves

  37. GALAXIES

  38. 3 TYPES • SPIRAL- 2-4 arms • EX. ANDROMEDA • IRREGULAR – • EX. MAGELLANIC CLOUDS • ELLIPTICAL

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