NATS 1740 Study Guide - Stellar Parallax, Inverse-Square Law, Binary Star

• School: York University
• Department: Natural Science
• Course: NATS 1740
• Professor: Patrick Hall

Document Summary

Parallax the apparent shift in position of a nearby object against a background of more distant objects. Apparent positions of nearest stars shift by about an arcsecond as earth orbits sun. Parallax is measured by comparing snapshots taken at different times and measuring the shift in angle to star. The smaller is the parallax shift, the greater is the distance to the star. Luminosity total amount of power a star radiates (energy per second, measured in watts) (apparent) brightness amount of power per area that reaches earth (energy per second per square meter =watts/m2) Inverse square law the equation of relationship between apparent brightness and luminosity. Luminosity = brightness / [4 p (distance) 2] The light from any star is spread out over a sphere surrounding the star and the luminosity passing through any sphere centered on the star is the same.