PHYS1160 Lecture Notes - Lecture 5: Radial Velocity, Proper Motion, Gas Gas

• School: UNSW, UNSW Sydney
• Department: Physics
• Course: PHYS1160
• Professor: Dr Jimmy Carl

Document Summary

Refers to the band of light which can be seen spanning the sky on a dark night. Further studies revealed the milky way to be a vast system containing billions of stars, as well as clouds of dust and gas. Dark regions are clouds of dust - obscure our view of the stars. As a result we can"t see all of our galaxy at visible wavelengths. Centre bright region of stars called the bulge. Spiral arms: made from gas and stars. Disk of stars is very thin - 100k light years across + Globular clusters - clusters of millions of stars. Radial velocity - velocity of a star along our line-of-sight direction using doppler effect. Proper motion - motion of a star perpendicular to our line-of-sight using astrometry. From these measurements we can determine the orbits of various types of stars. Disk stars have roughly circular orbits (keeping close to yellow line).