Fig. 16-3, p.316

1. Pinwheel Galaxy Spiral Fig. 16-3, p.316

2. Andromeda (Spiral) Galaxy with two companion elliptical galaxies Fig. 16-4, p.317

3. Four types of galaxies have been identified by shape: Masses in units of Milky Way galaxy. Elliptical galaxies: E0 to E7. E0 is spherical and E7 highly elliptical in shape. Contains very old, relatively less massive stars and have very little gas and dust. Most common galactic type. Mass 0.001 to 50. Spiral galaxies: have central bulge and spiral arms. Have lots of gas and dust, mostly in the spiral arms. Mass 0.01 to 10. Spiral bar SB have a bar attached to central bulge. Milky Way galaxy is Spiral Bar Irregular galaxies: no particular shape but has lots of gas and dust. Typically smaller in mass than spiral galaxies. About few per cent of galaxies are irregular. Mass < 0.01 Large and Small Magellanic Clouds are Irregular Galaxies. Active (peculiar) galaxies, such as quasars. Few in numbers. Galaxy types

4. Hubble galaxy classification Fig. 16-6a, p.318

5. Hubble Types of Galaxies NGC = New General Catalogue Fig. 16-6b, p.318

6. Most likely all Elliptical and Spiral galaxies have central black holes. Some may have more than one black hole. Milky Way 2.6 Million Solar mass Andromeda M31 30 M32 3 NGC4261 400 M87 3,000 M104 1,000 NNGC 3377 100 Black Holes in Galactic Centers

7. NGC 4565, spiral Sb galaxy Fig. 16-7a, p.319

8. Sombrero galaxy M104 Fig. 16-7b, p.319

9. Spiral Bar galaxy SB Type NGC 1634 Fig. 16-8, p.319

10. M87 Giant elliptical galaxy Fig. 16-10a, p.320

11. Galactic Clusters • Most galaxies belong to clusters. • Number of galaxies in a cluster varies from 10 to 10,000. • Some small clusters are part of giant super clusters.

12. Local group has 25 galaxies Two large Spiral galaxies, Milky Way and Andromeda galaxy. Andromeda is 2.2 million light years away. Large and Small Magellanic Clouds are companion galaxies of the Milky way. LMC and SMC are small irregular galaxies. Galaxy ClustersLocal Group

13. Large Magellanic Cloud Irregular Galaxy Fig. 16-11a, p.320

14. Small Magellanic Cloud Irregular Galaxy Fig. 16-11b, p.320

15. Virgo Super Cluster has about 1,000 galaxies, Local group is in this cluster Fig. 16-17, p.323

16. Coma super cluster with ~ 10,000 galaxies Fig. 16-18, p.323

17. Slice of Universe, 6 degrees Fig. 16-21a, p.324

18. Fig. 16-21b, p.324

19. Dark Matter Velocity depends of Kepler 3rd law and only on MASS. • The matter has gravity, but we do see it.

20. Jupiter size objects. Brown dwarf stars. Black holes. All of these objects create gravitational lensing. There are other possibilities of dark matter. Dark Matter possibilities

21. Gravitational lensing Fig. 16-24a, p.328

22. Gravitational Lensing

23. Gravitational lensing Fig. 16-25a, p.329

24. Gravitational lens pattern Not enough of large dark objects to account for the amount of dark matter in galaxies. Fig. 16-25b, p.329

25. Expansion of the Universe v in km/sec Hubble plot in 1929. Fig. 16-27a, p.331

26. Hubble Law 1931 v = H d Fig. 16-27b, p.331

27. Edwin Hubble Hubble Law v = H d H ~ 70 km/s/Mly Basis of Big Bang Theory (Model) Fig. 16-5, p.317

28. HST Deep Field in Big Dipper Fig. 16-28, p.334

29. Deep field with red shifts Fig. 16-30, p.334

30. Interacting (Colliding) Galaxies • Galaxies do collide, but distance of stars are so big that stars do not collide with each other. • Computer models of colliding galaxies show that the spiral arms can break off forming irregular galaxies. Antennae galaxies Interacting Spiral Galaxies

31. Cartwheel Galaxy ring caused by satellite galaxy interaction Fig. 16-13, p.321

32. Computer model of Interacting Galaxies Fig. 16-35, p.337

33. The Mice, NGC 4676 Collision of two galaxies p.314