The predominant color of the flora and plant organisms of a planet in relation to the type of star it orbits and the wavelength it generates.

[NormaVega]

Today any scientist or person with a minimum of general knowledge in astronomy knows that there is more than one type of star in the universe. Using the example of our star, the Sun, we know that it is a type G2 star (yellow dwarf) and has a luminous magnitude V (standard). But we assume that this is not the only type of star, below I will show a brief summary of the different types of stars that are out there:

 

Spectral Type O:

Temperature: 30,000°K - 50,000ºK

Color blue.

Luminosity: Very high.

Mass: Large.

Examples: Rigel, Zeta Orionis.

 

Spectral Type B:

Temperature: 10,000°K - 30,000°K

Color: Blue/White.

Luminosity: High.

Mass: Large.

Examples: Regulus, Spica.

 

Spectral Type A:

Temperature: 7,500°K - 10,000°K

White color.

Luminosity: Moderate.

Mass: Medium.

Examples: Sirius, Vega.

 

Spectral Type F:

Temperature: 6,000°K - 7,500°K

White/Yellow.

Luminosity: Moderate.

Mass: Medium.

Examples: Procyon, Canopus.

 

Spectral Type G:

Temperature: 5,000°K - 6,000°K

Yellow color.

Luminosity: Moderate.

Mass: Medium.

Examples: The Sun, Alpha Centauri A.

 

Spectral Type K:

Temperature: 3,500°K - 5,000°K

Orange.

Luminosity: Low.

Mass: Small.

Examples: Epsilon Indi, Epsilon Eridani.

 

Spectral Type M:

Temperature: 2,400°K - 3,500°K

Red color.

Luminosity: Very low.

Mass: Small.

Examples: Proxima Centauri, Barnard's Star

 

 

Here is the link to Wikipedia about the classification and star types in case anyone interested is curious about this classification: https://en.wikipedia.org/wiki/Stellar_classification

 

Once we have learned the types of stars, we must know how we are going to relate this to the predominant color that will reflect the flora of a planet. 

To begin with, we must know that the relationship between the color of a plant and the wavelength of the light it absorbs is determined by the pigments present in the plant, such as chlorophyll (very present and important here on Earth), which they selectively absorb. certain wavelengths of light to carry out photosynthesis.

As with the various types of stars, there are also many types of pigments that have their unique and exclusive light absorption/reflection characteristics of the visible spectrum, below I will show you a brief summary of each of the pigments. most important and abundant in nature:

 

Chlorophyll a:

Absorbing color: Mostly absorbs in the blue and red ranges.

Reflecting color: Mainly reflects green.

Absorbed wavelength: About 430 nm (blue) and 662 nm (red).

 

Chlorophyll b:

Absorbing color: Absorbs in the blue and red ranges, although it does so slightly differently than chlorophyll a.

Reflecting color: It also mainly reflects green.

Absorbed wavelength: About 453 nm (blue) and 642 nm (red).

 

Carotenoids:

Absorbing color: They absorb mainly in the blue range and some green wavelengths.

Reflecting color: They reflect colors ranging from yellow to orange.

Absorbed wavelength: Varies depending on the type of carotenoid, but generally around 400-550 nm.

 

Phycoerythrin:

Absorbing color: Absorbs strongly in the blue range.

Reflecting color: Mainly reflects red.

Absorbed wavelength: About 495 nm.

 

Phycocyanin:

Absorbing color: Absorbs in the blue and orange ranges.

Reflecting color: Mainly reflects blue.

Absorbed wavelength: About 620 nm.

 

 

And again I leave you a link to a better explanation of biological pigments in case you are curious: https://letstalkscience.ca/educational-resources/backgrounders/plant-pigments

 

And now of course you will be wondering what it has to do with or how it is possible to relate the types of plant pigments with the type of star, because it is easier than you think, with something that was mentioned in both topics: the wavelength.

 

We place ourselves in the panorama in which by relating each type of star with the wavelengths they emit and the possible plant pigments adapted to those wavelengths, we are considering how the light available in the stellar environment can influence the evolution of the plant life on those planets. Plants need these specific pigments to absorb the light energy necessary for photosynthesis and other biological functions similar to it.

For example, in star systems where ultraviolet and blue wavelengths predominate, such as type O and B stars, it would be advantageous for plants to develop pigments that can efficiently capture that light. On the other hand, in star systems dominated by longer wavelengths, such as K- and M-type stars, plants could benefit from pigments that absorb in the red and infrared range.

 

Below I show you my more detailed diagram with each of the star types and their relationship with the plant pigments:

 

Type O and B stars:

They emit a large amount of light in the ultraviolet and blue spectrum.

Plant pigments that could be relevant:

• Phycobilins: These pigments absorb strongly in blue and could be useful in capturing the intense blue and ultraviolet light emitted by these stars.

• Carotenoids: Although they primarily absorb in the blue and green range, they can also play a protective role against UV radiation damage.

 

Type A and F stars:

They emit light in a wide range of colors, with a peak in blue-green.

Plant pigments that could be relevant:

• Chlorophyll a and b: These pigments are mainly responsible for photosynthesis and absorb light in the blue and red ranges, which allows them to efficiently take advantage of the light emitted by these stars.

 

G-type stars:

They emit light mainly in the visible spectrum, with a peak in the yellow-green.

Plant pigments that could be relevant:

• Chlorophyll a and b: They continue to be the dominant pigments, as they effectively absorb light in the blue and red ranges, which are present in sunlight.

 

K and M type stars:

They emit light at longer wavelengths, including orange, red, and infrared.

Plant pigments that could be relevant:

• Phytoerythrin: This pigment, which absorbs strongly in the red, could be useful for capturing the light emitted by these K and M type stars.

• Carotenoids: In addition to their role in protecting against ultraviolet radiation, some carotenoids can also absorb in the red range, which could be beneficial in red- and infrared-dominant light environments.

 

Coming to the end and as a conclusion to this small project that I have just proposed to you, although the stellar and pigment classification is correct, we must keep in mind that before discussing the vivid tones of the flora in other worlds, we have to go through many filters so that both plant and animal life can occur.

And we also have to take into account that there are many other factors that can influence the appearance of life itself and can even vary, outside of classifications, the pigments of plants, as occurs in many plants on Earth, especially on flowers and parasitic plants.

 

Dario GM.

 

[Eise]

I think you can rule out O and B type stars. They live too short that life on a planet orbiting such a star can develop:

[NormaVega]

6 hours ago, Eise said:

I think you can rule out O and B type stars. They live too short that life on a planet orbiting such a star can develop:

Certainly, but don't rule out all possibility of life since the theory of panspermia proposes that life can be transported through space by comets, meteorites and other celestial bodies, which suggests that life could have reached a planet orbiting that kind of stars. This implies that the short lifespan of type O or B stars does not necessarily rule out the possibility that life could develop on a planet within their orbit.

Here you have a link to the panspermia theory if you are curious: https://en.wikipedia.org/wiki/Panspermia

Edited April 3 by NormaVega

[swansont]

1 hour ago, NormaVega said:

Certainly, but don't rule out all possibility of life since the theory of panspermia proposes that life can be transported through space by comets, meteorites and other celestial bodies, which suggests that life could have reached a planet orbiting that kind of stars. This implies that the short lifespan of type O or B stars does not necessarily rule out the possibility that life could develop on a planet within their orbit.

Here you have a link to the panspermia theory if you are curious: https://en.wikipedia.org/wiki/Panspermia

But organisms from panspermia would be adapted to their home world. And the lifetime of the star ignores formation time of any planets, which would likely have to cool before life could survive on them.

[NormaVega]

46 minutes ago, swansont said:

But organisms from panspermia would be adapted to their home world. And the lifetime of the star ignores formation time of any planets, which would likely have to cool before life could survive on them.

It is true that panspermic organisms could have evolved in very different conditions than planets around class O or B stars. However, life's ability to adapt to a variety of environments is remarkable, and it is plausible that the imported organisms, and even more so in the case (very likely) that these are microorganisms and/or Extremophilic bacteria for the mere fact that they are organisms that have been traveling for a considerable amount of time on small celestial bodies through deep space, can adjust to the conditions of these still very hot planets in a surprisingly short period of time.

[swansont]

1 hour ago, NormaVega said:

It is true that panspermic organisms could have evolved in very different conditions than planets around class O or B stars. However, life's ability to adapt to a variety of environments is remarkable, and it is plausible that the imported organisms, and even more so in the case (very likely) that these are microorganisms and/or Extremophilic bacteria for the mere fact that they are organisms that have been traveling for a considerable amount of time on small celestial bodies through deep space, can adjust to the conditions of these still very hot planets in a surprisingly short period of time.

But Earth’s Hedean era lasted ~500 million years, so if that’s similar for other planets you don’t have habitable planets for O and B type stars. 

Other habitability issues arise as well - for hotter stars, the “Goldilocks” zone is farther away, but the far planets in the solar system are gas giants, not rocky ones like the inner planets. If that’s true elsewhere, it makes A type stars an iffy proposition.

 

[NormaVega]

1 hour ago, swansont said:

But Earth’s Hedean era lasted ~500 million years, so if that’s similar for other planets you don’t have habitable planets for O and B type stars. 

Other habitability issues arise as well - for hotter stars, the “Goldilocks” zone is farther away, but the far planets in the solar system are gas giants, not rocky ones like the inner planets. If that’s true elsewhere, it makes A type stars an iffy proposition.

 

Yes, in that you are right since the possibility of a planet being habitable around these stars is practically zero, but we cannot deny the existence of a planet, no matter how far away it is and cold it may be, that plant that can give gives rise to some type of photosynthetic or extremophilic bacteria on the ice or cold rocky surface that presents the pigments discussed (according to classification) on the surface of that planet in orbit far from the star, but with reception (even if it is scarce) of the light that generates that type of star, knowing that the luminosity of type B stars is approximately 20,000 times the luminosity of the Sun and class O stars with a luminosity more than 1 million times stronger than that of the Sun.

[MigL]

Quote from Jurassic Park  "Life will find a way ".

The thing about life is that it adapts.
Not to color of the parent star, but to the wavelength of highest intensity in the star's spectrum.
Our sun, for example, emits a skewed bell shaped distribution of radiation, rising rapidly in the long wavelength region, peaking in the visible light wavelength, and trailing off gradually in the short wavelength region.
It is no wonder that life on this planet evolved such that our eyes are most sensitive to visible light wavelengths, and that plants make use of the more abundant energy source at those same wavelengths.

The skewed bell shaped intensity curve is called the characteristic black body radiation curve for the temperature of the emitting surface. For a blue/white star like Spica, the peak of its curve may be in the ultraviolet range, so life ( ? ) on a planet orbiting Spica, would not be adapting to a particular color, or chemical process, but would need to adapt to extreme amounts of UV radiation.
Similarly, life on a planet orbiting a blue star like Rigel might have to adapt to even shorter wavelengths, not only UV, but also some amounts of x-rays, which would necessitate totally different chemical processes, as x-rays can ionize loosely bound electrons.

[Moontanman]

This idea of life conforming to the wavelength of light can be seen in plants that grow deep under water. Various colors of plants grow at various depths taking  advantage of the filtering of light by water. By the time you get down to around 30 feet red light all but vanishes, blood is florescent green not red and plants that grow deep underwater are various colors from red to brown to yellow. Various pigments are used to supplement chlorophyll and even shift light from UV to visible light all to harvest the sun as efficiently as possible. 

I see no reason this wouldn't happen on other planets under the light of strange stars. 

[NormaVega]

21 hours ago, Moontanman said:

This idea of life conforming to the wavelength of light can be seen in plants that grow deep under water. Various colors of plants grow at various depths taking  advantage of the filtering of light by water. By the time you get down to around 30 feet red light all but vanishes, blood is florescent green not red and plants that grow deep underwater are various colors from red to brown to yellow. Various pigments are used to supplement chlorophyll and even shift light from UV to visible light all to harvest the sun as efficiently as possible. 

I see no reason this wouldn't happen on other planets under the light of strange stars. 

That is the case, the possibility that the planets that orbit those stars have had the option and enough time to be able to have some type of ocean, or similar to the primitive soup of the hydronic beginnings of the Earth, and at that point the Life could, as you say, evolve to anchor itself to light seabeds, that is, algae.

[exchemist]

23 hours ago, Moontanman said:

This idea of life conforming to the wavelength of light can be seen in plants that grow deep under water. Various colors of plants grow at various depths taking  advantage of the filtering of light by water. By the time you get down to around 30 feet red light all but vanishes, blood is florescent green not red and plants that grow deep underwater are various colors from red to brown to yellow. Various pigments are used to supplement chlorophyll and even shift light from UV to visible light all to harvest the sun as efficiently as possible. 

I see no reason this wouldn't happen on other planets under the light of strange stars. 

Blood? In plants? Or are you thinking of haemolymph in crustaceans? That is blue/green, but not because of anything to do with light absorption.

[Moontanman]

2 minutes ago, exchemist said:

Blood? In plants? Or are you thinking of haemolymph in crustaceans? That is blue/green, but not because of anything to do with light absorption.

No I was talking about my blood, if you ever get cut below 30 feet or so the blood will be fluorescent green!

[Genady]

13 minutes ago, Moontanman said:

fluorescent green

Hmmm... My blood is just dark green there. Not fluorescent at all.

[exchemist]

55 minutes ago, Moontanman said:

No I was talking about my blood, if you ever get cut below 30 feet or so the blood will be fluorescent green!

Oh I see, because of the light at such a depth. Why fluorescent, though?

[Moontanman]

58 minutes ago, Genady said:

Hmmm... My blood is just dark green there. Not fluorescent at all.

 

17 minutes ago, exchemist said:

Oh I see, because of the light at such a depth. Why fluorescent, though?

I honestly have no clue, I know that at depth red light is gone and my blood was bright green with a yellowish florescence to it. I try to take care not to cut my self underwater but that one time I gashed myself pretty good and bled like a stuck pig. The liberty ship I was diving on was full of sharp metal and swimming around through the ship was likely to get you cut at least slightly. On a positive side I did manage to get some interesting glass glass jugs that had been sunk as garbage when the ship was intentionally sunk. 

I remember quite clearly swimming across the deck with sunlight glinting all-around me and being surrounded by a cloud of fluorescent green blood.  

[Ken Fabian]

A different opinion here. I expect that the light from other stars will still have a lot of energy across the whole visible spectrum, that eg Blue stars don't make only blue nor have a pronounced lack of red light in the spectrum and Chlorophyll a and b would work just fine.

Despite the amount of energy available to Earth plants between Red and Blue they have not evolved photosynthesis that utilises Green effectively, despite the great abundance of green light - the limitations may be in the kinds of photosynthesis chemistry that work and the other, non chlorophyll sorts of photosynthesis (some not doing CO2 to O2) are less effective. Maybe plants elsewhere will manage with Red and Blue photosynthesis (and look green like here)  because those kinds of photosynthesis are easier for biochemistry to achieve.

Edited April 4 by Ken Fabian

[CharonY]

15 minutes ago, Ken Fabian said:

Despite the amount of energy available to Earth plants between Red and Blue they have not evolved photosynthesis that utilises Green effectively, despite the great abundance of green light - the limitations may be in the kinds of photosynthesis chemistry that work and the other, non chlorophyll sorts of photosynthesis (some not doing CO2 to O2) are less effective. Maybe plants elsewhere will manage with Red and Blue photosynthesis (and look green like here)  because those kinds of photosynthesis are easier for biochemistry to achieve.

Not really a plant person, but I think it is a bit of a misconception that plants do not use green light effectively. It is just utilized slightly differently. One important finding is that green light penetrates deeper into tissue, providing energy for CO2 fixation in deeper within leaves. Studies also suggest that because of that (and because of the rather steep absorption profile, this deeper penetration is more effective rather than trying to absorb more blue/red light closer to the surface. I think there are quite a few studies out there regarding the overall quantum efficiency at different wavelengths and different intensities in relation to plant architecture and distribution of chloroplasts, but I think the the idea that the rather simplistic idea of low absorptance of green light and associated low levels of CO2 assimilation that is sometimes still taught is school is a fair bit outdated (and goes back to studies in the 70s, I believe).

But again, not my field of expertise but there is a rather large body of literature on this topic.

 

Edit: found two reviews on the topic (only skimmed the abstract, but rings a bell to what I heard as student): 

https://doi.org/10.1093/jxb/erx098

https://doi.org/10.1093/pcp/pcp034

 

 

[Moontanman]

5 minutes ago, Ken Fabian said:

A different opinion here. I expect that the light from other stars will still have a lot of energy across the whole visible spectrum, that eg Blue stars don't make only blue nor have a pronounced lack of red light in the spectrum and Chlorophyll a and b would work just fine.

Despite the amount of energy available to Earth plants between Red and Blue they have not evolved photosynthesis that utilises Green effectively, despite the great abundance of green light - the limitations may be in the kinds of photosynthesis chemistry that work and the other, non chlorophyll sorts of photosynthesis (some not doing CO2 to O2) are less effective. Maybe plants elsewhere will manage with Red and Blue photosynthesis (and look green like here)  because those kinds of photosynthesis are easier for biochemistry to achieve.

You do make a good point, the color of a star reflects its peak output, the fact that the star emits a range of light with just the peak defining its color. Our own sun should, by that peak color thinking, be greenish but there are no green stars, the rest of the sun's spectrum washes out the green peaks. 

I tried to look this up but no joy, too many pages of the color of stars based on their spectrum on Google but... I saw recently where it is thought that if the Earth was placed around a red star or a blue blue star the color of the star would appear close to what we see from earth due to the peak temp being a peak that ignores the rest of the spectrum. Our own eyes would probably fool us into seeing a moreor less yellow sun in the sky. Evidently googling this requires more finesse than I have. 

Just now, CharonY said:

Not really a plant person, but I think it is a bit of a misconception that plants do not use green light effectively. It is just utilized slightly differently. One important finding is that green light penetrates deeper into tissue, providing energy for CO2 fixation in deeper within leaves. Studies also suggest that because of that (and because of the rather steep absorption profile, this deeper penetration is more effective rather than trying to absorb more blue/red light closer to the surface. I think there are quite a few studies out there regarding the overall quantum efficiency at different wavelengths and different intensities in relation to plant architecture and distribution of chloroplasts, but I think the the idea that the rather simplistic idea of low absorptance of green light and associated low levels of CO2 assimilation that is sometimes still taught is school is a fair bit outdated (and goes back to studies in the 70s, I believe).

But again, not my field of expertise but there is a rather large body of literature on this topic.

I would like to see a source for this please, it goes against everything I know about plants and photosynthesis. 

[CharonY]

4 minutes ago, Moontanman said:

I would like to see a source for this please, it goes against everything I know about plants and photosynthesis. 

Added two reviews in the post above. What I heard as student was, I believe, from a textbook related to bioenergetics, but I cannot recall the title (too long ago, likely in German). I only remember because it was fairly counter-intuitive, considering what was taught in high school. But considering what I learned about cellular efficiency since then, it makes a lot of sense.

Here are the abstracts from the links above:

 

Quote

The literature and our present examinations indicate that the intra-leaf light absorption profile is in most cases steeper than the photosynthetic capacity profile. In strong white light, therefore, the quantum yield of photosynthesis would be lower in the upper chloroplasts, located near the illuminated surface, than that in the lower chloroplasts. Because green light can penetrate further into the leaf than red or blue light, in strong white light, any additional green light absorbed by the lower chloroplasts would increase leaf photosynthesis to a greater extent than would additional red or blue light. Based on the assessment of effects of the additional monochromatic light on leaf photosynthesis, we developed the differential quantum yield method that quantifies efficiency of any monochromatic light in white light. Application of this method to sunflower leaves clearly showed that, in moderate to strong white light, green light drove photosynthesis more effectively than red light. The green leaf should have a considerable volume of chloroplasts to accommodate the inefficient carboxylation enzyme, Rubisco, and deliver appropriate light to all the chloroplasts. By using chlorophylls that absorb green light weakly, modifying mesophyll structure and adjusting the Rubisco/chlorophyll ratio, the leaf appears to satisfy two somewhat conflicting requirements: to increase the absorptance of photosynthetically active radiation, and to drive photosynthesis efficiently in all the chloroplasts. We also discuss some serious problems that are caused by neglecting these intra-leaf profiles when estimating whole leaf electron transport rates and assessing photoinhibition by fluorescence techniques.

Quote

The pleasant green appearance of plants, caused by their reflectance of wavelengths in the 500–600 nm range, might give the impression that green light is of minor importance in biology. This view persists to an extent. However, there is strong evidence that these wavelengths are not only absorbed but that they also drive and regulate physiological responses and anatomical traits in plants. This review details the existing evidence of essential roles for green wavelengths in plant biology. Absorption of green light is used to stimulate photosynthesis deep within the leaf and canopy profile, contributing to carbon gain and likely crop yield. In addition, green light also contributes to the array of signalling information available to leaves, resulting in developmental adaptation and immediate physiological responses. Within shaded canopies this enables optimization of resource-use efficiency and acclimation of photosynthesis to available irradiance. In this review, we suggest that plants may use these wavelengths not just to optimize stomatal aperture but also to fine-tune whole-canopy efficiency. We conclude that all roles for green light make a significant contribution to plant productivity and resource-use efficiency. We also outline the case for using green wavelengths in applied settings such as crop cultivation in LED-based agriculture and horticulture.

 

[Moontanman]

4 minutes ago, CharonY said:

Added two reviews in the post above. What I heard as student was, I believe, from a textbook related to bioenergetics, but I cannot recall the title (too long ago, likely in German). I only remember because it was fairly counter-intuitive, considering what was taught in high school. But considering what I learned about cellular efficiency since then, it makes a lot of sense.

Here are the abstracts from the links above:

 

 

Thank you, learning is why I am here! 

[CharonY]

Just now, Moontanman said:

Thank you, learning is why I am here! 

My pleasure.

[Ken Fabian]

@CharonY That is interesting and shows I don't know as much as I would like to. Thanks.

Some green light gets used by photosynthesis yet a whole lot of green light goes unused by Earth's dominant plants or it would be absorbed, not reflected nor pass through leaves so much; I am still inclined to think the biochemistries that can do photosynthesis well could be limited and stronger green light won't necessarily lead to plants that use more green light more effectively.

[TheVat]

15 hours ago, Moontanman said:

Thank you, learning is why I am here! 

That chloroplasts were using these wavelengths was news to me, as well.   One of those facts which, once you are aware of it, everything makes more sense.   Especially in how foliage is optimizing its absorption within a shaded canopy where it needs to make the most of whatever light is getting through.  Nature finds a way.  A plus one to Charon for bringing this...to light.  

[Moontanman]

1 hour ago, TheVat said:

That chloroplasts were using these wavelengths was news to me, as well.   One of those facts which, once you are aware of it, everything makes more sense.   Especially in how foliage is optimizing its absorption within a shaded canopy where it needs to make the most of whatever light is getting through.  Nature finds a way.  A plus one to Charon for bringing this...to light.  

It does bring some things into focus that I have wondered about as well! 

18 hours ago, Genady said:

Hmmm... My blood is just dark green there. Not fluorescent at all.

 

17 hours ago, exchemist said:

Oh I see, because of the light at such a depth. Why fluorescent, though?

I've given this some more thought and I wonder if the florescent part could have been because I was just at the limit of red light and might have had a bit of yellow left in the glitter flashing around the deck of the liberty ship I was exploring. 

[exchemist]

9 hours ago, Moontanman said:

 

I honestly have no clue, I know that at depth red light is gone and my blood was bright green with a yellowish florescence to it. I try to take care not to cut my self underwater but that one time I gashed myself pretty good and bled like a stuck pig. The liberty ship I was diving on was full of sharp metal and swimming around through the ship was likely to get you cut at least slightly. On a positive side I did manage to get some interesting glass glass jugs that had been sunk as garbage when the ship was intentionally sunk. 

I remember quite clearly swimming across the deck with sunlight glinting all-around me and being surrounded by a cloud of fluorescent green blood.  

I wonder if that could be an effect caused by a mix of reddish and greenish light, appearing to the eye as a yellow tint. I don't think anything in blood will actually fluoresce, not least because the UV will be attenuated under water more than visible light.

But the way light is attenuated by seawater seems to be quite complicated. The red end of the visible spectrum seems to be absorbed more than the green and blue, but UV is also absorbed. And then there is the competing phenomenon of scattering which will scatter the blue more than the red.