120 likes | 347 Views
Classifying Galaxies. By: Mary Lange. Edwin Hubble. November 20, 1889 – September 28, 1953 An American astronomer Confirmed other galaxies existed The first to categorize galaxies. Hubble’s Galaxy Classification.
E N D
Classifying Galaxies By: Mary Lange
Edwin Hubble • November 20, 1889 – September 28, 1953 • An American astronomer • Confirmed other galaxies existed • The first to categorize galaxies
Hubble’s Galaxy Classification The 3 Major Galaxy Classifications • Spirals • Elliptical • Irregulars
Spiral Galaxies • Flattened galactic disk • Spiral arms • Central galactic bulge • Dense nucleus • Extended halo • Faint, Old stars • Newer Stars • Example: • Milky Way Galaxy • Andromeda
Elliptical Galaxies • No galactic disk • No spiral arms • Little or no bulge • Dense central nucleus • No halo • Less evidence for young stars
Irregular galaxies • Do not fit into any other category! • Rich in interstellar matter • Young Blue Stars • Lack Regular Structure
The Tuning Fork of Hubble Sequence 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
Bright Galaxies • 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.
Bright Galaxies • 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)
Bright Galaxy • 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
References • Ewert, Michael. Astronomy 162. N.p.: University ofTennesse, n.d. N. pag. Web. 6 Dec. 2011. <http://csep10.phys.utk.edu/astr162/lect/index.html>. • 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. <http://www.oneminuteastronomer.com>.