Color of Alien Plants

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Color of Alien Plants

Post by NuclearVacuum on 19th February 2009, 5:57 pm

I have been reading about this over and over again. They all say the same thing, a planet around a red dwarf stars would most likely have black colored plants, while a planet around an F main sequence star would be more towards the red color. But what about other stars? Like K stars. B and O stars I can understand leaving blank.

Is there some pattern that I am missing?

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Re: Color of Alien Plants

Post by Sirius_Alpha on 19th February 2009, 6:42 pm

It's probably a continuum from black to lighter colours. M, and K stars emit less energetic light, so plants will have to be darker to absorb it better. F, and A stars emit higher energy light, so plants need to be a lighter colour to avoid being cooked.

As for B and O stars, I don't know if plants would be possible. Those stars are heavy on UV output, which tends to damage, DNA.

Have any studies been presented about the habitability of OB stars?

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Re: Color of Alien Plants

Post by marasama on 4th March 2009, 4:36 am

It's possible. Just won't be plants as we know it.

Likely the plants would be very white or very shiny to reflect as much light as possible.
Might even made a materials like silicon. Since glass reflect UV light.

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Re: Color of Alien Plants

Post by marasama on 4th March 2009, 4:40 am


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Re: Color of Alien Plants

Post by jbjerk on 19th November 2009, 3:43 pm

The general idea is that plants would be colored to absorb (and thus convert to energy) the strongest color wavelengths from their star.

this Nasa article breaks down the different wave lengths of light that would reach the surface of an earth-like world. Unfortunately it's hard to read.

As for alien plants under high-UV stars, there are several ways they might cope, assuming their DNA is also shredded by UV.

* Grow under water

* Close up under full sunlight, and open only while cloudy, or dawn and dusk

* Take sunlight indirectly, bounced off a reflective surface, or even the ground that absorbs or scatters UV
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Re: Color of Alien Plants

Post by Diakonov on 19th November 2009, 9:10 pm

Earth-like planets around M stars may have black or dark purple plants, as I believe. But they may be bright in near infrared! Such plants might be bright in waveleghts that we don't see. Also animals in such planets, if they have eyes, might see mostly in the near infrared. Insect-like creatures might see in the visible light spectrum and mammals or reptiles in near infrared.

Animals would see in NIR because that's most part of the light produced by such stars. And I think that animals living in worlds orbiting F stars would see mostly in UV rather than visible light. Maybe insects seeing in X-ray? But that's not probable, since X-rays break DNA. Or life in such worlds are based on something different from DNA, more resistent to support UV? Maybe PNA?

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Re: Color of Alien Plants

Post by jbjerk on 20th November 2009, 12:16 am

Diakonov wrote:Earth-like planets around M stars may have black or dark purple plants, as I believe. But they may be bright in near infrared!...
No, they would almost certainly be dark in near IR. If they were bright in IR that would mean they are reflecting away the only plentiful wavelength of light, instead of absorbing the energy and using it.


Anything with eyes would almost certainly see in IR or at least red, since there's extremely little blue, green, or yellow light to see.


Last edited by jbjerk on 20th November 2009, 12:17 am; edited 2 times in total (Reason for editing : clarity)
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Re: Color of Alien Plants

Post by Diakonov on 20th November 2009, 11:06 am

Yes, you're right. If M stars produce more NIR, plants can't be bright in NIR. Maybe in visible light. Or maybe plants could be bright in lower frequencies of light, maybe in middle infrared... or not.

But I saw in http://www.mi.infm.it/manini/dida/BlackBody.html?textBox=50000 that, for example, that a M star with 3500 K would not produce much blue, but still much green and yellow. So I really don't think that a M0V or M5V star planet would be totally red, because at such temperatures the main color is yellow, not red. If the air is similar to Earth, the sky would be green or yellow. Or even may still have some blue, a dark blue almost black. But more probably cyan!

But a M9V star planet would be redder, because at 2500 K almost no blue is produced, but the predominant light is still yellow. And a Earth-like planet sky would be not blue... maybe yellow or green.

And a brown dwarf with average temperature of 1500 K would be really red, so any planet orbiting it would be red to our eyes, and the sky also red.

Planets orbiting M stars would be more yellow or green, not red. But planets orbiting L and T stars would really be red, very red!

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Re: Color of Alien Plants

Post by ciceron on 20th November 2009, 12:03 pm

I just discard any kind of complex live like plants in a planet around an OB Star. There's no time for that kind of evolution in a star that brigth before it becomes unstable.

Even if evolution it's frenetic in a high radiation enviroment like that , just take this in consideration. There is no such thing as constant behavior for a star. There is always some process going on that alters his througput somewhat , like darkspots , and fusion process are stadistical , so energy output can displace a few decimals below 0.01 %.

On a medium-sized, well behaved star like our sun , that % is not really that important , and earth layers of protecion (magnetic and atmospheric, and , in the case of sea , water) , can buffer it without as much as a blink , it they are of short duration. Higher order perturbations can have some pretty dramatic results , as glaciations and global warmings , that disperse in mere tenths of thousand years

But in OB stars , a 0.0001 % desviation of energy output would wipe out the most resilient lifeform ever devised , not to mention , evolved.

My take is , O,B,A stars have next to 0 probability of having any lifeform , not to even consider complex constructs as plants, except maybe on the lower A types , under a big layer of buffeting fluid , and far away of the parent star ....and for a short time before the star goes postal.

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Re: Color of Alien Plants

Post by jbjerk on 20th November 2009, 12:44 pm

Diakonov wrote:...But I saw in http://www.mi.infm.it/manini/dida/BlackBody.html?textBox=50000 that, for example, that a M star with 3500 K would not produce much blue, but still much green and yellow. So I really don't think that a M0V or M5V star planet would be totally red, because at such temperatures the main color is yellow, not red. If the air is similar to Earth, the sky would be green or yellow. Or even may still have some blue, a dark blue almost black. But more probably cyan!

But a M9V star planet would be redder, because at 2500 K almost no blue is produced, but the predominant light is still yellow. And a Earth-like planet sky would be not blue... maybe yellow or green.

A star's color isn't precisely the same as a blackbodies is it?

Your statements don't seem to mesh with this nasa chart, though i admit i was looking at the M4.5V and M5V stars and missed the M1V when i made the statements in the previous post. It shows pretty plainly the output of M stars as being strongest in the red or IR.

This chart also factors in an atmosphere, which may cause some of the difference.
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Re: Color of Alien Plants

Post by Lazarus on 20th November 2009, 4:05 pm

I once did a simulation of what happens if you take black body spectra for various temperatures and applied a 1/λ4 filter to simulate Rayleigh scattering.

Unfortunately I've subsequently lost both the program and the output (probably lurking on a backup drive somewhere) - but as I recall for Gliese 581, the Rayleigh-scattered sky colour comes out as very pale blue. Haven't checked what effects clouds or haze would have though.

For stars much cooler than that, the sky colour ends up turning orangey-red. Of course this doesn't factor into account various absorption lines that start becoming significant at lower temperatures: the blackbody approximation starts breaking down. IIRC the very broad sodium absorption lines start to make brown dwarfs appear more magenta.

As for plants having the absorption mainly in the region that the star outputs: consider what colour a lot of the vegetation on Earth is, and where the peak emission is for the Sun... maybe suggests that maximum absorption of energy is not the primary selecting factor, and maybe things like potential for overheating may also be relevant.

Also, not all plants/photosynthetic organisms on Earth are green.
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Re: Color of Alien Plants

Post by jbjerk on 21st November 2009, 2:46 pm

Lazarus wrote:As for plants having the absorption mainly in the region that the star outputs: consider what colour a lot of the vegetation on Earth is, and where the peak emission is for the Sun... maybe suggests that maximum absorption of energy is not the primary selecting factor, and maybe things like potential for overheating may also be relevant.

Also, not all plants/photosynthetic organisms on Earth are green.

I'll agree that maximum absorption isn't the only factor. But the importance would no doubt vary based on the availability of other wave-lengths. Looking at the chart, it seems that G (and to a lesser degree, K) stars have a relatively even distribution of light in our visible range. M and F stars are much more strongly skewed to one end of our visible spectrum.

I realize that the sun's peak emission is in green, but according to the article, once you factor in the atmosphere, there's more red available for plants.

Previously, scientists thought plants are not efficient as they could be, because they do not use more green light.

According to scientists, the Sun has a specific distribution of colors of light, emitting more of some colors than others. Gases in Earth's air also filter sunlight, absorbing different colors. As a result, more red light particles reach Earth's surface than blue or green light particles, so plants use red light for photosynthesis.




Here's an interesting article on sky color that deals with a few other factors such as pressure.
http://www.orionsarm.com/xcms.php?r=oa-page&page=gen_skyonalienworlds
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Re: Color of Alien Plants

Post by Sunchaser on 3rd March 2013, 10:17 am

What about this? It seems to make sense to me that the plants would reflect the peak wavelength/color and therefore appear that color...

http://planetstar.wikia.com/wiki/Forest_planet

Only a thought...

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Re: Color of Alien Plants

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