Other Galaxies and Dark Matter - Other Galaxies and Dark...

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Other Galaxies and Dark Matter the gas and dust in the disk of the galaxy absorbs and scatters much light o can’t see very far at visible wavelengths We seem to be at the center based on counting stars in different directions o fooled because they didn’t know how much dust and gas there was that obscured our view Harlow Shapley determined we are not at the center of the Milky Way o noticed that globular clusters seem very concentrated in one direction o assumed that they orbit the center of the galaxy o determined our distance by plotting the placement of the clusters Edwin Hubble – observed Cepheid variable stars o evolved supergiant stars that brighten and fade periodically as their size oscillates o observed these stars to be very faint first thought that it could be because of dust if this were true they would have appeared red must be extremely distant – found them to be outside of the Milky Way o from the distance and angular size deduced that they are huge galaxies
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This note was uploaded on 04/04/2008 for the course ASTRO C 10 taught by Professor Filippenko during the Fall '08 term at University of California, Berkeley.

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Other Galaxies and Dark Matter - Other Galaxies and Dark...

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