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Stellar Blackbody + Absorption Lines

What you are seeing: the Planck continuum (yellow) shifts with TT (Wien's law); on top, characteristic stellar absorption lines (H Balmer, Ca II H&K, Na D, Mg b) cut into the spectrum. Sliding TT lets you sweep through OBAFGKM-type stars and see the peak migrate from UV through visible to IR.

Figure 1. Continuum + line spectrum vs T.
T (K)5800
line depth1.0
scale

WHAT TO TRY

  • Slide the temperature T: the Planck continuum brightens and its peak marches to shorter wavelengths (Wien law), so the star colour shifts from red toward blue. The lambda_peak readout tracks it.
  • Deepen the absorption lines: the Balmer, Ca II H and K, Na D and Mg b features cut into the continuum. Their depths are what a real spectral classification reads to type the star.
  • Switch the wavelength scale to log: the far-infrared tail spreads out so you can see the continuum fall, while the visible band strip marks where the eye actually sees the colour.