Abstract:
The physics of the Doppler Effect, Blackbody radiation, and spectra allow us to determine many properties of stars. These include how fast the star rotates, if it is a binary star, what elements are present, and what temperature it is. We will demonstrate these principles, and participants will make paper towel tube spectrometers to take home.
Outline:
1. Temperature and Color: The Electromagnetic Spectrum
Demo with light and dimmer
"blackbodies" blackbody
applet -- drag temp, see graph change
2. Why things look the colors they do
• reflection vs. filters
Demo using grating on overhead projector and filters and opaque objects and Glo-Doodler
3. Spectral Lines
• lines and elements -- fingerprints
• how absorption lines are formed ??
Spectra: Examples from Dr. Richmond
Neon spectrum (others linked).
Daylight and bulbs -- from Ioannis Galidakis 1
• How spectra work: Hands-On Atom
Shows em/abs spectra for all elements.
Build spectrometer ...
• H-R diagram and spectral classes H-R Diagram image.
4. Doppler simulation?? Link from worksheet [brief tutorial] ambulance going by
Doppler Effect Δλ/λ = v/c
• redshift [=z] when moving away;
• blueshift when moving toward
Doppler identifies spectroscopic binary stars.
Line Profile/Broadening
• rotation of stars
• thermal broadening
• density in stellar atmosphere -- pressure broadening
5. Finale Galaxy Song -- Monty Python video version