Plant life under a red sun

[Spaceception]

Going from the dimmest type of Red dwarfs )Say Wolf 359) to the brightest )Say Lalande 21185), what would the plant life on Earthlike exoplanets look like )Assuming it's very similar to Earth in terms of everything, but it doesn't have to be exact)? Obviously, it'll be much darker than our plants, but how dark? And could our plant life adapt to it? And what would its biology be? Or it's possible functions?

 

Btw, this is for my book idea, but I'm not restricting it to just that.

Edited March 14, 2016 by Spaceception

[Mitchz95]

Stephen Baxter's "Proxima" depicts an Earth-like planet orbiting Proxima Centauri. The planet is tidally locked and has vegetation with black leaves because there's not as much visible light coming from the star. Not sure how realistic that is.

EDIT: Wikipedia "confirms":

Quote

Having to adapt to a far wider spectrum to gain the maximum amount of energy, foliage on a habitable red dwarf planet would probably appear black if viewed in visible light.

https://en.wikipedia.org/wiki/Habitability_of_red_dwarf_systems

Edited March 14, 2016 by Mitchz95

[Spaceception]

Just now, Mitchz95 said:

Stephen Baxter's "Proxima" depicts an Earth-like planet orbiting Proxima Centauri. The planet is tidally locked and has vegetation with black leaves because there's not as much visible light coming from the star. Not sure how realistic that is.

EDIT: Wikipedia "confirms":

https://en.wikipedia.org/wiki/Habitability_of_red_dwarf_systems

I've read that book, but is there any other types of plant that could grow under a star like Lalande? I hoping it could be a dark red

Also, I can't access Wikipedia for some reason.

[lajoswinkler]

Darkness is less important here. The fact red quanta are less energetic is much more important. Life would need to adapt to these, absorbing as much energy as possible. Somehow I think these plants would look pretty close to pitch black in white light.

[fredinno]

7 minutes ago, Spaceception said:

I've read that book, but is there any other types of plant that could grow under a star like Lalande? I hoping it could be a dark red

Also, I can't access Wikipedia for some reason.

Those would reflect red light, which is what red dwarfs produce the most, so yeah. Anything but.

[Mitchz95]

A planet with black plants would probably look really neat from orbit. Especially if its skies and oceans are blue like Earth's.

[Spaceception]

Just now, Mitchz95 said:

A planet with black plants would probably look really neat from orbit. Especially if its skies and oceans are blue like Earth's.

The skies and oceans would look tan or orangeish, the light is too dim for it to look blue, although, I may be wrong for the brighter end of the red dwarfs.

[K^2]

20 minutes ago, Spaceception said:

The skies and oceans would look tan or orangeish, the light is too dim for it to look blue, although, I may be wrong for the brighter end of the red dwarfs.

The star needs to be at least orange-yellow to get enough blue for a blue tint on things. I think it would qualify as a yellow dwarf by that point. I would expect something in brown-orange-tan sort of colors for water and sky. With black vegetation and what likely appear to human eye as red ice caps. What a sight!

[Mitchz95]

Now I wish I knew how to make planets in Kopernicus. I really want to make this planet and play around with it in KSP.

[K^2]

1 hour ago, Mitchz95 said:

Now I wish I knew how to make planets in Kopernicus. I really want to make this planet and play around with it in KSP.

You'd probably need to make an entire star system with a red dwarf sun to make it authentic. Not that it really has to have anything besides that planet and a few rocks.

P.S. If anybody actually wants to try this out, I can easily crunch numbers for a particular spectral type and tell you exactly what color sky, water, ice, etc. should be.

Edited March 14, 2016 by K^2

[daniel l.]

I think the sky and water would be red because unlike, the sun which is a white star, red stars produce red light and cant be atmospherically scattered.

[problemecium]

I recall seeing a special long ago that said red dwarfs' plants would be black, but as to what color "black," my best guess would come from using color theory:

Earth plants are green because they primarily absorb red light, and also a bit of blue; on a scientifically-accurate color wheel (not an artist's!), the opposite of red is cyan, and the opposite of blue is magenta. So starting at cyan and shifting a bit toward magenta on the wheel yields green.

A red dwarf would emit a different spectrum from the Sun, particularly a more uh, red one. If we assume our Sun is more or less pale yellow, then shifting over to red is about 1/6th of the wheel or one secondary color over. Shifting green over by the same amount yields yellow plants that absorb mainly infrared and also cyan or green light. If we darken them to enhance the infrared absorption, that more or less yields brown. So I'm picturing a planet covered in plants that look dead and rotten o_O

[Spaceception]

Just now, K^2 said:

You'd probably need to make an entire star system with a red dwarf sun to make it authentic. Not that it really has to have anything besides that planet and a few rocks.

P.S. If anybody actually wants to try this out, I can easily crunch numbers for a particular spectral type and tell you exactly what color sky, water, ice, etc. should be.

I would like to know what the atm/water/ice/and plants would look like under the light Lalande 21185

@K^2

Edited March 15, 2016 by Spaceception

[DBowman]

google solar spectrum and photosynthesis frequency spectrum.

The sun peaks in light blue and has a big fat tail into infra red. Chlorophyll uses blue/violet and red, carotenoids use light blue. Photosynthesis will still 'work' chemically down to about 1% of Earth normal intensity. So our plants should do ok under a red dwarf (as long as it bright enough) but would look pretty much black. Apparently there are some infra red chlorophyll users ( from wired ) recently discovered - I guess they'd look black also. Flowers & fruits could be various reds though.

[K^2]

4 hours ago, DBowman said:

google solar spectrum and photosynthesis frequency spectrum.

The sun peaks in light blue and has a big fat tail into infra red. Chlorophyll uses blue/violet and red, carotenoids use light blue. Photosynthesis will still 'work' chemically down to about 1% of Earth normal intensity.

It would work, but it wouldn't be most efficient. Given these sort of conditions, I would expect different light-absorbing molecules to evolve. And most likely, what little of light is in visible red would probably be thoroughly absorbed. Now, if there is local fauna with different sort of vision, it might see actual "color" to the plants. But to us, it will look black or dark brown in all likelihood.

[Bill Phil]

Depends.

There once were red plants on Earth. But they're all gone, now. Mostly, at least.

The star is somewhat orangeish. Even red dwarfs aren't actually red. Our sun is the strongest in the green area of the spectrum... But the spectrum is muddled in the atmosphere. It depends o where the least amount of light is on the spectrum. At sea level on Earth, red and green are probably the lowest.

 

17 hours ago, daniel l. said:

I think the sky and water would be red because unlike, the sun which is a white star, red stars produce red light and cant be atmospherically scattered.

It's actually orangeish, at least in the visible spectrum.

You see, it emits light in ALL parts of the spectrum. But there's more red and other lower energy parts of the spectrum. 

[Stargate525]

Secondary question: how fast would those suckers grow in our sunlight (assuming atmospheric and ground conditions the same). Would they grow like kudzu because of all the extra energy, or would they burn?

[lajoswinkler]

2 hours ago, Stargate525 said:

Secondary question: how fast would those suckers grow in our sunlight (assuming atmospheric and ground conditions the same). Would they grow like kudzu because of all the extra energy, or would they burn?

It should wreck their photosynthesis molecular mechanisms. The quanta impacting the molecules would bash it into pieces.

 

On the subject of color, question is what the plants would look like under their parent star, and what would they look like under white light. There should be a difference.

Edited March 16, 2016 by lajoswinkler

[Creature]

5 hours ago, lajoswinkler said:

It should wreck their photosynthesis molecular mechanisms. The quanta impacting the molecules would bash it into pieces.

 

What do you think is the reason why this would happen? Assuming they're made of similar organic structures as plants here, why would the molecules break? The molecular bonds are the same strength and proteins hold together just fine under our light so I don't see why the molecules would start breaking apart.

If their photosynthesis uses primarily red to infrared spectrum, the most important factor is the difference in intensity at the absorbing spectrum between our star and their home star. If it's much greater here, the biochemical kinetics could possibly be overwhelmed and cause a myriad of problems but if it's about the same, there should be no issues. This of course is also dependant on how far from the parent star their home planet is.

So taking for example the near-IR, let's say 900 nm wavelength. What's the intensity of 900 nm light on Earth and could there be a planet at some reasonable distance from a red dwarf so that the intensities would be the same?

Another thing that could be a factor is if their home world has low levels of UV, then they might not be adapted to it. I'm not a botanist but plants on Earth have adapted to all kinds of different conditions so it's probably more a question of evolution. There is no underlying law of nature saying they couldn't thrive here, it's just a matter of details wether or not they can or can not adapt and would some other random factor here cause their death.

[lajoswinkler]

1 hour ago, Creature said:

What do you think is the reason why this would happen? Assuming they're made of similar organic structures as plants here, why would the molecules break? The molecular bonds are the same strength and proteins hold together just fine under our light so I don't see why the molecules would start breaking apart.

If their photosynthesis uses primarily red to infrared spectrum, the most important factor is the difference in intensity at the absorbing spectrum between our star and their home star. If it's much greater here, the biochemical kinetics could possibly be overwhelmed and cause a myriad of problems but if it's about the same, there should be no issues. This of course is also dependant on how far from the parent star their home planet is.

So taking for example the near-IR, let's say 900 nm wavelength. What's the intensity of 900 nm light on Earth and could there be a planet at some reasonable distance from a red dwarf so that the intensities would be the same?

Another thing that could be a factor is if their home world has low levels of UV, then they might not be adapted to it. I'm not a botanist but plants on Earth have adapted to all kinds of different conditions so it's probably more a question of evolution. There is no underlying law of nature saying they couldn't thrive here, it's just a matter of details wether or not they can or can not adapt and would some other random factor here cause their death.

Why would you assume the photosynthetic machinery would be made the same? It clearly needs to be more sensitive in order to be reactive with (probably) water when exposed to weak quanta. Throwing UVA, violet and blue at it should cause damage, just like some bacteria's molecules are damaged even by blue light.

Compare it to photoelectric effect on metallic lattices. You can throw as many wrong photons at it as you want, but unless you get the one with enough energy, you won't eject an electron out of it.

Near infrared is very abundant on Earth during daylight. Most plants repel it strongly so they look like this when the view is represented in monochrome.

 

On a world where near infrared and red are the only plentiful light available, special dyes would evolve, being able to harness weak quanta of light. Bash their complex molecules even with small amounts of more energetic photons and they would get damaged.

Compare it to a world orbiting a blue star where plants have evolved to endure lots of blue, violet and UV. Put our plants there and their protein machinery would break apart.

[Spaceception]

Just now, lajoswinkler said:

I can't view it.

[AngelLestat]

Well, if the planet is far from the star maybe as the topic said plants would evolve to try to absorb all the energy they can, but photosynthesis as we know it does not need all the wave spectrum, only certain bands, so being complete dark will not bring any benefit, because they are absorbing energy which they can not use and also these increase the release of heat under the night, when it may be important to retain some of that heat.

So a possible solution would be achieve a perfect black body in the day (using thin dark live hairs like a nanotube forest), using water circulation or other elements to store all that heat into the soil.
When the night hours appear, the hairs will reorganize to change the emissivity to an infrared reflectance, and the water will keep circulating to provide heat needed for other survival reasons.

But in that world of perfect dark the 3d shapes at certain distance will disappear like in this picture:

[Xorth Tanovar]

On 3/14/2016 at 4:29 PM, Mitchz95 said:

A planet with black plants would probably look really neat from orbit

Until you get closer and realize they're not plants at all.....anyone remember Larry Niven's "Bordered in Black?"

[luizopiloto]

In such planet... there will be no vegetables... only fungus... Mushrooms everywhere... or just Ice...

[Creature]

2 hours ago, lajoswinkler said:

Why would you assume the photosynthetic machinery would be made the same? It clearly needs to be more sensitive in order to be reactive with (probably) water when exposed to weak quanta. Throwing UVA, violet and blue at it should cause damage, just like some bacteria's molecules are damaged even by blue light.

Compare it to photoelectric effect on metallic lattices. You can throw as many wrong photons at it as you want, but unless you get the one with enough energy, you won't eject an electron out of it.

Near infrared is very abundant on Earth during daylight. Most plants repel it strongly so they look like this when the view is represented in monochrome.

<snipped the image>

On a world where near infrared and red are the only plentiful light available, special dyes would evolve, being able to harness weak quanta of light. Bash their complex molecules even with small amounts of more energetic photons and they would get damaged.

Compare it to a world orbiting a blue star where plants have evolved to endure lots of blue, violet and UV. Put our plants there and their protein machinery would break apart.

 

I thought we assumed Earth-like plantlife and surroundings. Of course if the biochemistry is somehow exotic, then it's a whole different discussion. I'm sorry but most of what you're saying just doesn't make much sense. In photosynthesis plants capture light by chlorophylls, which is a generic term for an organic molecule that covers several variations of the same basic structure. It has two major absorption bands at blue and yellow-red areas (hence the color).

The absorption spectrum is defined by the molecular structure. There are tons of pigments that absorb at near-IR for example. It doesn't work at all like you described. The pigment doesn't have to be "more sensitive" in any way, it just needs a different absorption band. Obviously the energy of longer wavelength radiation is much smaller, hence it's not a good source of energy for photosynthesis and the associated biochemistry would be different. I think there was a mention somewhere in Wikipedia about some plants even using IR for photosynthesis, but I won't vouch for it's accuracy.

In any case, the light absorbing molecule is still just a regular carbon-based organic molecule and their photobleaching properties are a completely separate issue. For example you can't just "bash" an IR-dye with UV kill it like you suggest. First of all it doesn't catch the UV light very well, it just passes over it. This is also a nice property, because it can be used for spectrophotometry. Second thing is that even if it would absorb it (and be an UV pigment instead), it would probably withstand our UV levels just fine since organic pigments do that fairly well in general. Unless you propose that the covalent bonds are somehow weaker around red dwarfs?

The reason why UV is dangerous for living things is because DNA has absorption maximum at 260 nm, which means that as long as the exoplants have DNA, they are susceptible to UV induced cell damage. This has zero to do with photosynthesis. Like I said, it's possible that life developing around a red dwarf might be ultra sensitive to UV, but it's just as likely that it would have the same resistance to it as any domestic plant. But since it's already hard to say if a plant from Siberia would live when transferred to Mongolia, it's impossible to say these things about a fictional exoplant.