kellylepo,
@kellylepo@astrodon.social avatar

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.

1/

Image credits
Toaster: https://commons.wikimedia.org/wiki/File:Toaster_Filaments.JPG
DSS image of Betelgeuse: https://www.eso.org/public/images/eso0927e/

A bright reddish-orange star. The star shows a typical diffraction pattern for a bright star seen through a telescope - a circle in the center and four thin spikes forming a cross shape. In the background are thousands of smaller, fainter stars, seen as points of light in shades of blue and white on a black background.

kellylepo,
@kellylepo@astrodon.social avatar

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

2/

kellylepo,
@kellylepo@astrodon.social avatar

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.
3/

Figure from: https://spie.org/news/1199-a-cool-light-bulb?SSO=1

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