The Electromagnetic Spectrum and information from the Stars

1. The Electromagnetic Spectrum and information from the Stars • X-ray image of the sun

2. Electomagnet (EM) Specrtrum • All radiation, radio wave and light are part of the EM spectrum • Visible light is only a very small section of the whole spectrum

4. Simpler version of the EM spectrum

5. Wavelength- Distance covered by one full cycle of a wave- commonly measured crest to crest • CU physics site animation shows wavelengths • http://www.colorado.edu/physics/2000/waves_particles/index.html

6. Relative size of wavelengths

7. Arecibo • The Arecibo radio telescope in Puerto Rico is the largest single dish telescope in the world. • This 1000 foot dish was constructed over a natural crater. (= 0.3km = 0.2 mi)

8. Radio antenna and radio telescopes are large to pick up long wavelengths

10. VLA • The very large array in Socorro New Mexico was built in the 1970’s. • It uses 27 radio telescopes all linked together in a Y shape. These telescopes simulate a large radio telescope 40 km in diameter.

13. The SETI Project • SETI stands for the Search for Extraterrestrial Intelligence. • SETI began using the Arecibo telescope to look for alien signals. • In 1974 the Arecibo telescope sent a megawatt signal to outer space.

15. Frequency- How often a complete wave passes a set point #waves/time = cycles/sec = Hertz (Hz) • Long wavelength = low frequency • Short wavelength = high frequency

16. Energy in the wave • Long wavelength = low frequency = low energy • Short wavelength = high frequency = high energy

17. Fill in your own chart:

18. Spectra are created from excited electrons in atoms • Valence electrons absorb energy from heat, electricity, other EM emissions • Electrons jump up to a higher energy level • When electrons “fall” back to ground state they give off EM emisions

19. Kinds of spectrum • Continuous spectrum- like the rainbow • Absorbtion Spectrum - has rainbow with “black” lines in it • Emmission spectrum – just a line or two or three…………. Of colored light

21. Types of Galaxies- draw in • Elliptical • Spiral • Irregular

22. Doppler Effect • Red Shift-move away • Lengthen wavelength • Color shifts toward red end • Blue shift-move toward • shorten wavelength • Color shifts toward blue end

23. Mass of the universe determines fate • More than critical mass  collapse Big Crunch  another Big Bang? Does the universe occilate? Closed universe Less than critical mass  expands forever  Open universe

24. HR diagram • Graphs stars Temp (color or spectral class) vs Absolute magnitude (Luminosity) Absolute magnitude – brightness based on being the same distance away from each star Apparent magnitude – brightness from Earth- all stars are different distances away

25. HR Diagram Temp degrees C

26. Put colored stars of appropriate size on your chart

27. Layers of the Sun

28. Micro-Wave & Infra-Red Telescopes

29. 2 Famous Telescopes • In the 1960” Robert Wilson & Arno Penzias won the Noble Prize for their discovery with the first large microwave telescope. • COBE was a microwave / infra-red satellite in the 1980’s.

33. Visible “Optical” Telescopes • Early history of optical telescopes. • Modern day observatories. • The future of optical telescopes.

34. Yerkes Observatory • Built in 1897 the Yerkes telescope in Wisconsin is the largest refractor. • It has 40 inch diameter lens!

36. The Mt. Wilson Hooker Telescope • In 1908 the largest reflector telescope was built on Mt. Wilson overlooking Los Angeles. • This Hooker telescope uses a 100 inch mirror to collect light.

40. The Palomar Observatory, Hale Telescope • In 1948 the largest telescope was the 200 inch Hale telescope on Palomar Mountain, California.

43. The BTA Telescope • Currently the largest single mirror telescope is the BTA, (Bolshoi Teleskop Azimutal) in Southern Russia. • The BTA was built in 1975 and uses a single 230 inch mirror to collect light!

46. Multiple Mirror Telescopes • After building the huge BTA telescope, astronomers realized that 200 inches is the maximum size for a telescope. Anything larger than 200 inches and the mirror becomes distorted under its own weight. • The solution to this problem was to build multiple mirror telescopes.

47. Multiple Mirror Telescopes • M.M.T. combine many mirrors to form one giant mirror. These mirrors are computer controlled to make a parabolic shape. • The KECK telescope in Hawaii is currently the largest telescope in the world with a total of 400 inches of segmented mirrors!