Star Color and Temperature

astronomy simulation

Instructions: Use the slider or text input to set the temperature of the star.
Explanation: Stars have different colors when we observe them. The color we see is related to the temperature of the star and can be simulated using Planck's Blackbody Spectrum. The relation between intensity and wavelength is plotted in the lower half of the display. (The intensity has been normalized so the max value is always the same). $$B_{\lambda }(\lambda ,T)={\frac {2hc^{2}}{\lambda ^{5}}}{\frac {1}{e^{hc/(\lambda k_{\mathrm {B} }T)}-1}}$$ The visible range of the spectrum is color coded by wavelength. The to left of this area is the UV part of the spectrum, and to the right is the infrared region, neither of which we can see with our eyes.
Some example temperatures
  • Our Sun - 5772 K
  • Betelgeuse - 3500 K
  • Rigel - 11000 K
  • Sirius - 9940 K

Link to stand-alone sim: Here is a link to view the sim on its own, with no distractions.

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star color
blackbody radiation
color and temperature

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  1. Blackbody temperature to RGB adopted from