Why are there no green stars?

[bryanl]

There are red, yellow, and white stars, but why no green ones?

 

[PottedMeat]

...weird never thought of that

this says there are, just swamped out

http://www.oneminuteastronomer.com/708/star-colors-explained/

So why are there blue stars, yellow stars, red stars, but no green stars? As it turns out, there are green stars, that is, stars that radiate much of their light in the green part of the spectrum. But the total combination of the full range of colors of a “green” star appears white to our eyes. If you pass the color from a whitish star through a prism, you’ll see all the colors, including green, spread out in a continuum.

 

[Rakehellion]

There are. Kind of. http://blogs.discovermagazine.com/badastronomy/2008/07/29/why-are-there-no-green-stars/#.UTyJzaWM5SU

 

[serpretetsky]

i like this question!

I'm not sure, but here is where I am starting my research:
http://www.mediacollege.com/lighting/colour/colour-temperature.html
http://www.google.com/imgres?imgurl...PbyAGp04CYAQ&um=1&itbs=1&sa=X&ved=0CDAQrQMwAw

 

[Ferzerp]

Because blackbody radiation will never produce a green hue (plenty of green light, but the resulting hue is overwhelmed by other wavelengths).

When you heat something, it goes red, orange, yellow, white, blue (as far as your eyes can tell).

(Mostly) because when it's green, it's also emitting lots of red, orange, yellow, etc. You end up seeing it as white.

edit: it also doesn't help that we're the least sensitive in the green wavelength range either.

 

[Rakehellion]

edit: it also doesn't help that we're the least sensitive in the green wavelength range either.

Actually, the eyes are most sensitive to green. That's why night vision goggles and old computer terminals are all green.

 

[Ferzerp]

Actually, the eyes are most sensitive to green. That's why night vision goggles and old computer terminals are all green.

Sorry yes, brain fart.

The reason is still that blackbody radiation peaking in the green range has enough yellow and red that it appears white, and not until the heat gets high enough that the radiation starts trailing off in the visible spectrum that only blue is left do we see a major shift from "white".

 

[pandemonium]

Good question. I think the answer is surprisingly very simple: there are very few simple elements that emit green light visibly in stellar nucleosynthesis. The majority of stars are comprised of hydrogen and helium. The 'simplest' element that emits green would be Boron, and it isn't known to be created by stellar nucleosynthesis.

See:
http://en.wikipedia.org/wiki/Emission_spectrum
http://en.wikipedia.org/wiki/Nucleosynthesis
http://en.wikipedia.org/wiki/Normal_star

Edit: I read the other responses too late and now I'm wondering if what I thought has any bearing on it, lol.

 

[Ferzerp]

Good question. I think the answer is surprisingly very simple: there are very few simple elements that emit green light visibly in stellar nucleosynthesis. The majority of stars are comprised of hydrogen and helium. The 'simplest' element that emits green would be Boron, and it isn't known to be created by stellar nucleosynthesis.

See:
http://en.wikipedia.org/wiki/Emission_spectrum
http://en.wikipedia.org/wiki/Nucleosynthesis
http://en.wikipedia.org/wiki/Normal_star

Edit: I read the other responses too late and now I'm wondering if what I thought has any bearing on it, lol.

Yes, stars are undergoing fusion, but that's not happening on the surface. Typically, the light we see is incandescent from the heat (produced closer to the center via the fusion).

 

[silverpig]

The answer has already been posted, but I'll re-affirm it: Green stars look white to our eyes.

 

[Mark R]

Sorry yes, brain fart.

The reason is still that blackbody radiation peaking in the green range has enough yellow and red that it appears white, and not until the heat gets high enough that the radiation starts trailing off in the visible spectrum that only blue is left do we see a major shift from "white".

It doesn't really trail off significantly in the visible spectrum.

The peak shifts first to blue, then UV then X-ray; but there is still substantial green and red.



The planckian locus for a black body radiator is shown on this color diagram. Infinite color temperature is a relatively pale blue.

 

[VirtualLarry]

The 'simplest' element that emits green would be Boron, and it isn't known to be created by stellar nucleosynthesis.

See:
http://en.wikipedia.org/wiki/Emission_spectrum
http://en.wikipedia.org/wiki/Nucleosynthesis
http://en.wikipedia.org/wiki/Normal_star

Edit: I read the other responses too late and now I'm wondering if what I thought has any bearing on it, lol.

I thought that all of the elements that we have on earth were created via steller nucleosynthesis. How did Boron get here if that were not true?

 

[John Connor]

I'm color blind, but when I see stars at night all I see is yellow. Is this true? Is it the atmosphere that does this?

 

[pandemonium]

I thought that all of the elements that we have on earth were created via steller nucleosynthesis. How did Boron get here if that were not true?

Heavier elements are created during massive explosions with vast amounts of energy causing nuclei to fuse, birthing even heavier elements.

One of the wiki articles I linked has a brief description of how they're created:

Supernova nucleosynthesis within exploding stars, is responsible for the abundances of elements between magnesium (A=24) and nickel (A=60).[1] Supernova nucleosynthesis is also thought to be responsible for the creation of elements heavier than iron and nickel, in the last few seconds of a type II supernova event. The synthesis of these heavier elements absorbs energy (endothermic) as they are created, from the energy produced during the supernova explosion. Some of those elements are created from the absorption of multiple neutrons in the period of a few seconds during the explosion. The elements formed in supernovas include the heaviest elements known, such as the long-lived primordial element radionuclides uranium and thorium.

 

[pandemonium]

I'm color blind, but when I see stars at night all I see is yellow. Is this true? Is it the atmosphere that does this?

Depending on the layering of man-made or natural occurences from the land or sea (smog, mist, humidity, etc...) the coloring will change promoting the color of the particulates in the air. Typically the atmosphere will distort light from stars and promote reds and oranges.

Are there a lot of industrial plants nearby: mills or processing plants? If you look at the sky where there's really good seeing (no light pollution from street-lights, neighborhoods, business; no pollutants from businesses or industries or heavy traffic) I'm sure you'd see more blues, reds, oranges and whites than just yellow.

 

[John Connor]

No, I'm in the North of Colorado and there are no processing plants, etc.

 

[pandemonium]

I see. Well, a good test would be to locate where a strongly blue or red star would be and see what color it appears as to you.

This list should get you started: http://en.wikipedia.org/wiki/Star_color

And to check where stars are unless you have SkyMap or similar app on your phone, you can use http://www.fourmilab.ch/cgi-bin/Yoursky. Your GPS would be ~40°N 105°W.

Don't forget it takes a while for your eyes to adjust. Usually after 10-15 minutes in the dark you can really start seeing colors of each star.