SCI238 Lecture Notes - Quasar, Cygnus A, Starburst Galaxy
9 Jul 2013
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Document Summary
Galaxies come in a wide range of types. Spirals (like our own milky way): with spiral structure, disks, gas and dust, active star formation. Ellipticals: large rounded balls of stars, with little gas and dust, no disks. Lenticulars: intermediate in type between spirals and ellipticals. with disks but no spiral arms, some small amount of gas and dust. Moons: but andromeda is 700 kpc (0. 7 mpc) away from us, its true (linear) diameter is >1014 times greater than the moon! lenticular galaxies have disc and bulge but no spiral arms or gas. Elliptical galaxies classified by ellipticity : elliptical galaxies vary greatly in size and mass, this galaxy contains many globular star clusters. Irregular galaxies have little symmetry, often include gas. Appearance flattened disk bulge spherical halo spiral arms disk bulge halo no disk no obvious structure lots 10-20% ellipsoidal distribution little or none. <0. 1% in disk 3-10% little or none 0-1%
