AST201H1 Lecture Notes - Lecture 9: Inverse-Square Law, Luminosity Distance, Neutrino

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST201H1
• Professor: Macdonald

Document Summary

Ast201 lecture 9: inverse square law: what comes out has less mass than what went in. Properties of stars: what we want to know: composition, mass. Luminosity distance size: mass and size not the same, density can be different history/future. What can we measure: position of star on sky, spectrum (light, apparent of brightness, absorption lines colour changing in all these things. Luminosity: amount of energy an object emits in a certain time. Luminosity of the sun: one solar luminosity or 1l . Feb 4, 2020 this small fraction determines the star"s apparent brightness as seen from earth the closer a star is to earth, the higher the fraction of its light we receive. The amount of light er receive from a star falls with the square of its distance aka . Of all the light a star emits, earth only receives a small fraction.