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Agenda: galaxies

Agenda: galaxies. The Milky Way Types of galaxies Finding distances to galaxies. Activity grades. Missing group numbers will result in lost points. Signatures will be required to receive credit. There are lots of unclaimed assignments—check my folder!

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Agenda: galaxies

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  1. Agenda: galaxies • The Milky Way • Types of galaxies • Finding distances to galaxies

  2. Activity grades Missing group numbers will result in lost points. Signatures will be required to receive credit. There are lots of unclaimed assignments—check my folder! WebCT grades are updated after each exam.

  3. Seeing the Milky Way CO: MolecularClouds Hydrogen Gas Interstellar Dust Stars: no blocking hot gas bubbles

  4. Is it like this? NASA

  5. Or this? AATB

  6. Or this? NOAO

  7. What we see:

  8. Another galaxy… NASA

  9. Compare

  10. Compare to this one

  11. Harlow Shapley (1885-1972) Looked at many globular clusters Determined their distance from us We are not at the center of the galaxy!

  12. We live in a spiral galaxy! Globular clusters Stars we can see Our solar system Our galaxy is centered about here

  13. Shape of our galaxy ESA

  14. Our black hole Crazy x-ray bursts! CHANDRA

  15. Our black hole Radio waves NRAO

  16. Hubble rocks!!! Edwin Hubble 1889-1953

  17. Our neighbor Andromeda R. Gendler

  18. Spiral galaxy

  19. Spiral galaxy on edge Dusty!! NOAO

  20. Barred Spiral Spiral arms start at the end of the bar. hubble space telescope

  21. Types of spiral galaxies Caltech

  22. Types of barred spiral galaxies Caltech

  23. Elliptical galaxy Globular clusters Contain mainly older stars David Malin

  24. Types of elliptical galaxies Rotation not uniform Caltech

  25. Irregular galaxy NOAO

  26. Irregular galaxy Some galaxies have asymmetric shapes, often because they are interacting with their neighbors. NGC4676, the “mice” HST

  27. Consider Hubble’s hypothesis: • Do galaxies evolve from elliptical to spiral? A. Yes B. No C. Cannot conclude Increasing age?

  28. Increasing age? Do galaxies evolve? • Ellipticals contain mainly older stars • Spirals contain much dust and gas

  29. Calculating distances to other galaxies • Cepheid variables • Type I supernovae • Hubble’s law

  30. Cepheid variables Cepheids are a standard candle. Discovered by Henrietta Leavitt. (photo: AAVSO) Gene Smith, UCSD/CASS

  31. Supernovae in 4 galaxies All Type I supernovae reach same maximum luminosity. Another standard candle! Harvard

  32. Summary Our galaxy—the Milky Way Spiral shape (mapped using clusters)! We have our own black hole! Galaxies classified by Hubble Elliptical Spiral Barred spiral Irregular Measuring distance to galaxies Cepheid variable stars Type I supernovae

  33. Team activity #8 Stellar evolution Make sure you label all LINES!

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