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ASTRONOMY

ASTRONOMY. Chapter 34 Galaxies. Discovery. Initially called spiral nebulae. In 1924 Edwin Hubble calculated the distance to some using Cepheid variables. Showed they were outside the Milky Way galaxy. Types of Galaxies. Galaxies are classified by their shapes. Elliptical

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ASTRONOMY

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  1. ASTRONOMY Chapter 34 Galaxies

  2. Discovery • Initially called spiral nebulae. • In 1924 Edwin Hubble calculated the distance to some using Cepheid variables. • Showed they were outside the Milky Way galaxy.

  3. Types of Galaxies • Galaxies are classified by their shapes. • Elliptical • About 1/3 of all galaxies • Range from nearly circular to elongated • Spiral • Majority of galaxies • Can be tight wound or loosely wound • Irregular

  4. Elliptical Galaxies http://www.boscobel.k12.wi.us/~schnrich/2_eliptical_galaxies.jpg

  5. Spiral Galaxies http://ionhealth.files.wordpress.com/2010/03/spiral-galaxy.jpg

  6. Spiral Galaxies

  7. Irregular Galaxies http://2009rt6scifadi.files.wordpress.com/2010/03/barnard.jpg

  8. Peculiar Galaxies • Peculiar galaxies are galaxies that look basically regular with some major deviation. • M82 is a starburst galaxy. http://thebigfoto.com/wp-content/uploads/2010/03/dlopez-m82-cigar-galaxy.jpg

  9. Hubble’s Classification http://www.patana.ac.th/secondary/science/anrophysics/astronomy_elective/images/HubbleGalaxyClassification.jpg

  10. Hubble’s Classification (IR) http://upload.wikimedia.org/wikipedia/commons/thumb/8/85/Galaxy_morphology.jpg/250px-Galaxy_morphology.jpg

  11. Black Holes • Many galaxies have black holes at their centers. • The one at the center of our Milky Way is believed to be about 4 million M˳. • Other more massive galaxies may have central black holes of 2 billion M˳ or more.

  12. Galaxies Collide http://www.spacetelescope.org/static/archives/posters/screen/ngc2207.jpg

  13. Clusters of Galaxies • Galaxies occur in groups and clusters • Groups have only a few galaxies • Clusters contain up to hundreds or thousands of galaxies. • Galaxies in a group or cluster are gravitationally connected • We are in a group of about 3 dozen galaxies called the Local Group

  14. Galactic Group http://www.astropix.com/IMAGES/SHOW_DIG/Hickson44_Galaxy_Group.JPG

  15. Cluster of Galaxies http://fisicafotograficaln.files.wordpress.com/2011/10/galaxy-cluster.jpg

  16. The Virgo Cluster http://apod.nasa.gov/apod/ap110422.html

  17. Clusters of Clusters • All of the nearby clusters are member of a cluster of clusters. • This is called supercluster

  18. Radio Galaxies • Some galaxies emit a lot of radio waves. • These are called radio galaxies. • Radio galaxies and those that emit strongly in the x-ray region are called active galaxies.

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