Ay123 Lecture I - Physical Properties

1
Ay 123 Lecture I - Physical Properties
wavelength
flux
Spectral energy distributions of bright stars can
be used to derive effective temperatures
2
Model atmospheres of varying Teff, g used to
fit data
Teff
flux
Wavelength(?m)
3
Stellar Spectral Energy Distributions
flux
Wavelength(Å)
4
Spectral Classification
Diagnostic spectral lines act as independent
measures of temperature in stellar atmosphere
provided surface gravity is known
5
Stellar Spectra Giants vs Dwarfs
Stars are a 2-D sequence! Giants are slightly
cooler than dwarfs of a similar spectral class
with redder continua. This is because line
strengths depend on Teff and g
G
K
6
Luminosity Classes
7
Overview of Stellar Evolution on H-R Diagram
8
Evolution During the Main Sequence
Zero Age MS