AST201H1 Chapter Notes - Chapter 15.1-15.3 : Dim Stars, Cosmic Dust, Starflight

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST201H1
• Professor: Bryan Gaensler

Document Summary

Form in great clouds of gas and dust. Each begins life with roughly the same chemical composition as the sun. Apparent brightness: brightness of a star as it appears to our eyes. Luminosity: total amount of power that a star emits into space. Compare amount of red and blue light coming from a star. Interstellar dust can affect apparent colours --> spectral lines = more. The amount of light received per unit area decreases with increasing distance by the square of the distance. Measure the amount of light per square meter received from a star, use inverse square law to calculate luminosity and can then calculate distance (or other way around) Use detector to record how much energy strikes per second. Dependent on perfectly straight path without interruption --> often clouds / dust that make light rays dimmer and star appear less bright overall. Small annual shifts in a star"s apparent position caused by earth"s motion around the sun.