In the recent telescope image released by NASA, some stars seem to be either more “warm toned” or “cool toned”. I’m just brainstorming but is it related to the distance from Earth? Or perhaps it’s dependent on the elemental makeup. Are they actually different colors or do we just perceive them that way? TIA
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People talking about redshift and blueshift are not wrong — but when talking about the image just released from the James Webb Space Telescope it’s not really relevant to your question.
All the galaxies in that photo are moving away from us, and are all redshifted by the Doppler effect. The JWST only captures infrared light to account for this, and also because infrared can pass through the interstellar medium (tiny amounts of matter and lots of radiation) better than visible light. But we can’t see infrared with the naked eye, so to make a full-color image they digitally “color correct” the image.
Basically they undo the shifting caused by the Doppler effect — reversing the redshift to bring the image closer to “true” color, what your eyes would see if the distance between earth and those galaxies was not expanding. So the reason the galaxies appear to be slightly different hue is actually due to the the stars that make them up, not due to the Doppler effect. Galaxies made primarily of hot, bright stars will be more blue, and those made of dim, cool stars will be more red.
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