ASTRO-110 Chapter Notes - Chapter 6: Type Ia Supernova, Lenticular Galaxy, Spiral Galaxy
Document Summary
Edwin hubble developed a system for classifying galaxies based on their apparent shape tuning fork diagram. Elliptical galaxies: differentiated by eccentricity, eo: spherical, e7: flattened. Spiral and spiral barred galaxies are classified by the size of bulge, tightness of spiral arms, and dustiness of disks. Type a has a considerable bulge, tight spiral arms and some dust. Type c has a small bulge, loose spiral arms and lots of dust lenticular galaxies have a disk and bulge, but no spiral arms and little to no dust irregular galaxies are those that don"t fit. Hubble"s galaxy classification is still used not but because of new insights (no simple classification scheme tells us anything useful, so we just use the original) Measuring distance is difficult. radar ranging and parallax are our only two direct ways of measuring distances, and these methods only work for relatively nearby objects.
