AST201H1 Lecture Notes - Lecture 9: Stellar Parallax, Inverse-Square Law

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST201H1
• Professor: Bryan Gaensler, C. Barth Netterfield, Ilana MacDonald

Document Summary

We have information about our sun, mostly because we have sent probes to measure things or observe the sun. However, we have information about distant stars that we have never sent probes to. What we want to know: surface temperature, composition, luminosity, distance, mass, size, history/future, age. These are not numbers that pop out when you look at the stars. What can we measure: position on the sky, light spectrum (apparent brightness, colour, absorption lines, changes in all these things (its brightness, colour and absorption lines can change overtime. ) From these simple things we are able to find many characteristics of stars. Remember: you can tell a star"s temperature by its colour. The bluer it is the hotter it is. Luminosity: the amount of energy an object emits per unit time. 4 * 10^26 w is the luminosity of the sun. (no need to know the exact number but just know the sun is brighter than light bulbs. )