1. C LASSIFYING G ALAXIES By: Mary Lange

2. E DWIN H UBBLE November 20, 1889 – September 28, 1953 An American astronomer Confirmed other galaxies existed The first to categorize galaxies

3. H UBBLE ’ S G ALAXY C LASSIFICATION The 3 Major Galaxy Classifications Spirals Elliptical Irregulars

4. S PIRAL G ALAXIES Flattened galactic disk Spiral arms Central galactic bulge Dense nucleus Extended halo Faint, Old stars Newer Stars Example: Milky Way Galaxy Andromeda

5. E LLIPTICAL G ALAXIES No galactic disk No spiral arms Little or no bulge Dense central nucleus No halo Less evidence for young stars

6. I RREGULAR GALAXIES Do not fit into any other category! Rich in interstellar matter Young Blue Stars Lack Regular Structure

7. T HE T UNING F ORK OF H UBBLE S EQUENCE This image shows how similar in appearance the galaxies appear to be.  E0- E7 are elliptical galaxies  SO are between the elliptical and spiral  S and SB are spiral galaxies  Sa – Sc are spiral galaxies  SBa – SBc are barred-spiral

8. Elliptical Galaxies No Disk- stars distributed though ellipsoidal volume Contain only old stars, no significant star formation in last 10 billion years Early type galaxies Stars have random orbits Spiral Galaxies Flattened disk of stars and gas, contains spiral arms Contains young and old stars with Ongoing star formation Late type galaxies Stars move in circular orbit around galactic center

9. B RIGHT G ALAXIES Seyfert Galaxy Discovered by Carl Seyfert in 1943. Resemble the “Normal Galaxy” All Energy is emitted from the galactic nucleus. 10,000 times brighter than our galaxy.

10. B RIGHT G ALAXIES  Radio Galaxy  Radio galaxies are in the elliptical family.  Emits energy from it’s lobes.  Differs from the Seyfert Galaxies  The wavelengths at which they radiate  Appearance  Emitting regions (Radio portion of the electromagnetic spectrum)

11. B RIGHT G ALAXY  Quasar Galaxy  Date back to much earlier periods of galaxy formation and evolution than other galaxies.  Share many properties of Seyferts and Radio Galaxies  Most energy is emitted in infrared spectrum  Jets and extended emissions

12. R EFERENCES Ewert, Michael. Astronomy 162. N.p.: University of Tennesse, n.d. N. pag. Web. 6 Dec. 2011..University of McMillan, Steve, and Eric Chaisson. Astronomy: A beginner's guide to the universe. sixth ed. San Francisco: Addison-Wesley, 2010. 404-29. Print. Ventrudo, Brian. One Minute Astronomer. N.p.: Brian Ventrudo, Ph.D., 2011. Web. 6 Dec. 2011..