How is your toaster like a cool star?
They both look red and glow because they are hot, dense objects, but they emit most of their light at infrared wavelengths.
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Image credits
Toaster: https://commons.wikimedia.org/wiki/File:Toaster_Filaments.JPG
DSS image of Betelgeuse: https://www.eso.org/public/images/eso0927e/
#astronomy #Astro101 #stars
Why red?
The red line on this plot shows the amount of light emitted per area vs. wavelength, for an object that is 3000 K (the surface temperature of a cool star). Although it emits mostly infrared light, it still emits some visible light. It emits more red light than blue, so it appears red to our eyes.
Play around with the simulation here:
https://phet.colorado.edu/sims/html/blackbody-spectrum/latest/blackbody-spectrum_all.html
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This is incidentally why old-fashioned incandescent light bulbs are so inefficient: the majority of the light they produce is invisible (to our eyes) infrared light.
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Figure from: https://spie.org/news/1199-a-cool-light-bulb?SSO=1
And finally, here is a neat demo, showing what happens if heat up a piece of metal and watch it glow with both visible light and infrared cameras: https://youtu.be/sUp_WZKZID4
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Demonstration of black body radiation, the Stefan-Boltzmann and Wien Laws.Recorded 2015 April 23 by Prof. Richard Pogge, The Ohio State University, Departmen...
Kelly Lepo
Dr Ashley J Ruiter (she/her)