Blackbody Radiance Calculations

This set of scripts creates blackbody distribution plots useful for physical science education (especially astronomy).

Since the units and annotation of blackbody plots found on the internet are often incorrect, this package is shared to provide educators and researchers with some tools to create plots for lectures and presentations. These scripts create 7 plots each, for energy vs. wavelength in various units:
1) Energy Density, (BB_EnergyDensity_Energy_vs_Wavelength.m)
2) Spectral Radiant Exitance (BB_SpectralRadiantExitance_Energy_vs_Wavelength.m), and 3) Spectral Radiance (BB_SpectralRadiance_Energy_vs_Wavelength.m).

For spectral radiance, additional spectra plotted include:
A) L(lambda,T) in BB_SpectralRadiance_Energy_vs_Wavelength.m
B) L(nu,T) in BB_SpectralRadiance_Energy_vs_Frequency.m
C) L_p(lambda,T) in BB_SpectralRadiance_Photons_vs_Wavelength.m
D) L_p(nu,T) in BB_SpectralRadiance_Photons_vs_Frequency.m

The examples provided are typical examples for stars, Wein's Law, basic entities, low temperatures, etc. Please be patient, they take a minute to plot.

There is also a lot of confusion about what is integrated for the Stefan-Boltzmann law. A script, StefanBoltzmannLaw.m, provides a worked example for total flux (W/m^2) and total radiance (W/sr m^2) as well as total photon exitance (photons/s m^2), and total photon flux (photons/s sr m^2).

The method of converting spectral radiance given in wavelength to that given in frequency, and to convert from frequeny to wavenumber is explained with one worked example in ConvertUnitsOfASpectrum.m

Finally, a star is modeled as a blackbody (ModelStar_betaUMi.m), and application of spectral filters to get an in-band radiance is illustrated (ModelStar_betaUMi_withJohnsonFilters.m). Blackbodies are very poor approximations to real stars, but illustrate some of the math involved.