Astronomy Notes – Unit 3a – Stars and Galaxies
q (1) Stars – great balls of fire!
o Some scientists believe stars have a life cycle of billions of years
§ Birth – nebula, protostar, cloud of gas of increasing pressure, temperature
§ Grow old – fusion burns up the fuel (hydrogen to helium)
§ Die – some expand (red giants), collapse (white dwarfs, black holes), burn out, explode (supernova)
o Characteristics: brightness, color, mass, diameter, age, composition
o Hertzsprung-Russell diagram
§ temperature vs. brightness
§ groups – giants, main sequence, white dwarfs
o Variable stars
q (2) Galaxies – super-sized solar systems
o Types: spiral, barred spiral, elliptical, irregular
o Milky Way
o Nearest – Large and Small Magellanic Clouds
o Andromeda Galaxy – visible to the naked eye
o Star clusters – open (Pleiades), globular
q (3) Galactic clusters