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We can never perceive a green star with our eyes alone without some sort of substrate between the two blocking the red and blue light emissions. This is because
by Rooster61 10y ago
We can never perceive a green star with our eyes alone without some sort of substrate between the two blocking the red and blue light emissions. This is because green falls smack dab in the middle of the visible light spectrum. When a star a appears blue, most of what is being emitted by the star is photons with a frequency that appears blue, and photons with a frequency of ultraviolet or higher. Same goes for red stars, except instead of ultraviolet, it emits frequencies in infrared and lower, resulting again in light that our eyes cannot pick up. We only see the red photons that our eyes are able to pick up.
If we could see further into the ultraviolet and infrared spectrum, "blue" and "red" stars would most likely disappear in favor of whatever colors blue+ultraviolet and red+infrared look like. This is what we see when we look at a white star. It's a star emitting most of its light in the green spectrum, but also emitting reds and blues, thus appearing white.
(Fun side note: Our sun is actually what a "green" star would look like if we could actually see them. It's white when viewed from space. It only changes colors and appears primarily yellow due several factors affecting the photons in our atmosphere. Absorbption of certain wavelengths, Rayleigh scattering, ect.)
- dhimes 10y agoWe can never perceive a green star with our eyes alone without some sort of substrate between the two blocking the red and blue light emissions. A doppler shift of a red or blue star would do it.
- empath75 10y agoNo. A stars spectrum is spread out. Stars that look red or blue are mostly in infrared or ultraviolet. If you doppler shifted it to the middle of the visual spectrum, it would look white, not green.
- wolf-rayet 10y agoThe spectra of Wolf-Rayet stars are characterized by bright emission (rather than absorbtion) lines. Maybe you could get something that looks more-green-than-not to human eyes with the right red- or blue-shift of the right WR star?
- Rooster61 10y agoHow so? A doppler shift would only shift the apparent wavelengths that are already present. For it to create a green star effect, it would need to actively remove the upper and lower ends of the star's spectra.
- kmm 10y agoBlack-body radiation has the interesting property that it is invariant under redshift. I.e. a redshifted black body spectrum stays a black body spectrum, but for another temperature
- andrewflnr 10y agoIs black-body the only spectrum for which that's true, i.e. could you (in principle) define it that way?
- kmm 10y agoNo, it's true for any spectrum which is a function of the ratio of frequency and temperature, as we can then shuffle the factor appearing due to redshift into the temperature. Apart from any constant prefactors, because those don't change the shape of the spectrum but just its absolute value.
- dhimes 10y agoAck! I can't edit so I'll say here- you guys are right. My mistake. :(