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University of Toronto St. George
Astronomy & Astrophysics
Stefan Mochnacki

Interstellar medium absorbs visible ultraviolet and infrared light Halo of our galaxy has globular clusters The sun in 28000 light years from the center of the universe Interstellar bubble are made from the winds of massive stars and supernovae Most star formation occurs in the spiral arms Elliptical galaxies are the most spherical in shape Elliptical galaxies are redder and rounder Cepheids are pulsating variable stars, and their pulsation periods are directly related to their true luminosities. Hence, we can use Cepheids as standard candles for distance measurements From the period-luminosity relation for Cepheids, he was able to determine the distance to Andromeda and show that it was far outside the Milky Way Galaxy stellar parallax is the most accurate way to determine the distance to a nearby star parallax, main-sequence fitting, Cepheid variables, Tully-Fisher relation, Hubbles law Observations at different distances show galaxies of different ages and therefore different stages of evolution. Galaxies were closer together in the past because the universe was smaller. the energy that powers radio galaxies, quasars, and other active galactic nuclei produced by gravity, which converts potential energy of matter falling toward a central black hole into kinetic energy, which is then converted to thermal energy by collisions among the particles of matter ** How do we know that there are intergalactic clouds between a distant quasar and us? We see hydrogen absorption lines at redshifts smaller than that of the quasar. How do we know that there is much more mass in the halo of our galaxy than in the disk? Stars in the outskirts of the Milky Way orbit the galaxy at much higher speeds than we would expect if all the mass were concentrated in the disk A large masstolight ratio for a galaxy indicates that on average, each solar mass of matter in the galaxy emits less light than our Sun gravitational lensing occur when masses distort space time, the fabric of the universe and massive objects can act as gravitational lenses that bend light beams passing nearby www.notesolution.com
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