<p>Purple and green star exists. For example, a blue supergiant star can have its surface temperature to 50000 K, which peaks at purple in the blackbody spectrum. However, our eyes are more sensitive to blue than purple, and the contrast between blue and purple in the spectrum is insignificant, therefore we see blue.</p>

<p>Also, check this article: <a href="https://parade.com/295384/marilynvossavant/can-stars-be-green-or-purple/" rel="nofollow noreferrer">https://parade.com/295384/marilynvossavant/can-stars-be-green-or-purple/</a></p>

CC BY-SA 4.0
2018-11-21T18:23:45.527Z
See https://astronomy.stackexchange.com/questions/10510/why-are-there-no-green-stars?rq=1
ProfRob
CC BY-SA 4.0
2021-06-29T10:57:49.220Z
Who upvoted and then selected this very wrong answer? Linking to Marilyn vos Savant can be a very bad idea; she has been dead wrong on a number of issues. There are no purple or green stars.
David Hammen
CC BY-SA 4.0
2021-06-29T12:30:04.993Z
"Color" does not mean "At which wavelength does the spectrum peak". Color is given by the _ratio_ of fluxes in different wavelength bands, and no blackbody spectrum has a ratio in the human wavelength bands given by our eyes' cones that we will perceive as purple or green.
pela
CC BY-SA 4.0
2018-11-21T16:06:10.413Z
2018-11-21T16:06:10.413Z
Kornpob Bhirombhakdi
<p>Short answer: most stars emit a very wide range of wavelengths, from MHz (radio) to gamma ray, <span class="math-container">$10^{19} Hz$</span>  -- albeit rather little of the latter. But what we see is the combined wavelengths that our retina responds to, and due to the blackbody curve, by the time there's enough energy/temperature to produce a lot of blue or violet photons, the number of yellow/red photons swamps them.  </p>

<p>The coldest stars appear red, as you mention, because the black body spectral peak is low enough that there isn't much at all in the green-to-violet range. </p>

<p>Now, if you take the light from the hottest stars and run it through a prism or grating spectrometer, you can see that there is blue/purple light included. </p>

CC BY-SA 4.0
2018-11-22T00:48:01.170Z
Individuals experience light at the blue end of the spectrum differently. Some individuals have "red" cones that are only sensitive to red, so all light at the blue end of the spectrum looks blue. Others have "red" cones that are also sensitive to light at the far-blue end of the spectrum. Since this light stimulates both their "red" and blue cones, they perceive it as purple.
Gerard Ashton
CC BY-SA 4.0
2018-11-21T15:04:06.700Z
2018-11-21T15:04:06.700Z
Carl Witthoft
<p>I know that we don't see green stars because in blackbody radiation star doesn't produce one spectrum.</p>

<p>The stars that have peaks in the green spectrum produce other spectrum in nearly same amout. This make them appear white.</p>

<p>If stars have peaks in the infrarad spectrum that has wavelength little longer than red.</p>

<p>We see those stars red because they produce red spectrum more than other visible spectrum.</p>

<p>But if stars have peaks in the ultraviolet spectrum that has wavelength little shorter than violet. Why don't we see those stars purple ?</p>

CC BY-SA 4.0
2018-11-21T18:25:05.177Z
See https://astronomy.stackexchange.com/questions/10510/why-are-there-no-green-stars?rq=1 The reason why purple stars don't exist is also explained by this colour chart.
ProfRob
CC BY-SA 4.0
2022-11-26T12:52:54.120Z
Do you actually mean violet not purple? [Spectral violet](https://en.wikipedia.org/wiki/Violet_(color)#:~:text=In%20optics%2C%20violet%20is%20a%20spectral%20color%3A%20It%20refers%20to,some%20of%20which%20humans%20perceive) is shorter in wavelength than blue is, clocking in at just 380 to 435 nanometers, whereas purple is how we see an interplay of red and blue and violet wavelengths.
tchrist
<star><spectra>
Why don't we see purple stars
Ro Theory
# Why don't we see purple stars

(Asked by: username_0 on 2018-11-21)

I know that we don't see green stars because in blackbody radiation star doesn't produce one spectrum.

The stars that have peaks in the green spectrum produce other spectrum in nearly same amout. This make them appear white.

If stars have peaks in the infrarad spectrum that has wavelength little longer than red.

We see those stars red because they produce red spectrum more than other visible spectrum.

But if stars have peaks in the ultraviolet spectrum that has wavelength little shorter than violet. Why don't we see those stars purple ?

**Tags:** star, spectra

> **Comments:**
> **username_1**: See https://astronomy.stackexchange.com/questions/10510/why-are-there-no-green-stars?rq=1 The reason why purple stars don't exist is also explained by this colour chart.  
> **username_2**: Do you actually mean violet not purple? [Spectral violet](https://en.wikipedia.org/wiki/Violet_(color)#:~:text=In%20optics%2C%20violet%20is%20a%20spectral%20color%3A%20It%20refers%20to,some%20of%20which%20humans%20perceive) is shorter in wavelength than blue is, clocking in at just 380 to 435 nanometers, whereas purple is how we see an interplay of red and blue and violet wavelengths.  

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## 2 answers

### Answer by username_3 on 2018-11-21. Score: 1 | Accepted answer

Purple and green star exists. For example, a blue supergiant star can have its surface temperature to 50000 K, which peaks at purple in the blackbody spectrum. However, our eyes are more sensitive to blue than purple, and the contrast between blue and purple in the spectrum is insignificant, therefore we see blue.

Also, check this article: <https://parade.com/295384/marilynvossavant/can-stars-be-green-or-purple/>

> **Comments:**
> **username_1**: See https://astronomy.stackexchange.com/questions/10510/why-are-there-no-green-stars?rq=1  
> **username_4**: Who upvoted and then selected this very wrong answer? Linking to Marilyn vos Savant can be a very bad idea; she has been dead wrong on a number of issues. There are no purple or green stars.  
> **username_5**: "Color" does not mean "At which wavelength does the spectrum peak". Color is given by the _ratio_ of fluxes in different wavelength bands, and no blackbody spectrum has a ratio in the human wavelength bands given by our eyes' cones that we will perceive as purple or green.  

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### Answer by username_6 on 2018-11-21. Score: 5

Short answer: most stars emit a very wide range of wavelengths, from MHz (radio) to gamma ray, $10^{19} Hz$ -- albeit rather little of the latter. But what we see is the combined wavelengths that our retina responds to, and due to the blackbody curve, by the time there's enough energy/temperature to produce a lot of blue or violet photons, the number of yellow/red photons swamps them.

The coldest stars appear red, as you mention, because the black body spectral peak is low enough that there isn't much at all in the green-to-violet range.

Now, if you take the light from the hottest stars and run it through a prism or grating spectrometer, you can see that there is blue/purple light included.

> **Comments:**
> **username_7**: Individuals experience light at the blue end of the spectrum differently. Some individuals have "red" cones that are only sensitive to red, so all light at the blue end of the spectrum looks blue. Others have "red" cones that are also sensitive to light at the far-blue end of the spectrum. Since this light stimulates both their "red" and blue cones, they perceive it as purple.  

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