1. 14 Galaxies Island Universes

2. 14 Copyright – FORS1 VLTI, European Southern Observatory

3. 14 Hubble Tuning Fork

4. 14 Ellipticals

5. 14 Huge No gas. No dust. No young stars. Nothing but old stars. –Random orbits.

6. 14 M 87 Copyright – Anglo-Australian Telescope Board Copyright - HST

7. 14 Hubble Tuning Fork

8. 14 Copyright – Adam Block, KPNO

9. 14 Spirals

10. 14 Like Milky Way. Disks and bulge. Young stars and old. Gas and dust. Stars forming. Stars dying. M81 and M82 – Copyright R. Gendler

11. 14 M63 Copyright – S. Miyazaki, Suburu

12. 14 NGC1365 Copyright – VLT

13. 14 M31 The Andromeda Galaxy Copyright – Jason Ware Copyright – S. Miyazaki, Suburu

14. 14 M33 – Copyright NOAO

15. 14 M51 - Copyright HST John P. Gleason

16. 14 NGC 4314

17. 14 NGC 891 – Copyright J.C. Barentine, NOAO NGC 891 – Copyright WIYN

18. 14 Sombrero Galaxy – Copyright P. Barthel VLT M10 – copyright Credner and Kohle

19. 14 NGC 4526

20. 14 Irregulars

21. 14 Nearby Galaxies Cepheids. Period. Luminosity  abs. mag. Know app. Mag Get Distance.

22. 14 Groups

23. 14 The Local Group

24. 14 Clusters

25. 14 The Virgo Cluster

26. 14

27. 14 NGC 1316 – Copyright VLT

28. 14

29. 14 Distant Galaxies Can’t see individual stars. Can use nearby galaxies to get distances to further galaxies. Distance ladder: –Parallax  nearby stars –Nearby stars  H-R diagram –H-R diagram  distant stars (variables) –Variable stars  nearby galaxies –Nearby galaxies  ?

30. 14 21cm Radiation Neutral hydrogen (HI) gives off radiation at 21cm. Milky Way HI emission – Copyright J. Dickey

31. 14 Extragalactic HI Observe HI in other galaxies. Measure wavelength of 21 cm radiation. Get velocity away from us.

32. 14 Hubble’s Law Measure the velocity of every galaxy. Nearly all are redshifted. Use Cepheids to measure distances to nearby galaxies. Result: The faster it’s moving, the farther away it is.

33. 14 Map the Universe V = H o D If you know H o : Measure v Get D Find: Voids Walls Clusters

34. 14

35. 14 Homework #12 Read: Bennett Ch 22.1 – 22.4 Do Ch22: –Problems: 1, 6, 9, 12 –Math folks substitute problem 18 for 9 and 12.