Let's create an alien biosphere!

[Schiaparelliorbust]

Photosynthetic organisms can use a variety of wavelengths of light. Phototrophs on Earth mainly absorb light in the visible spectrum only because that is the region of the electromagnetic spectrum in which the Sun emits the most light. Shorter wavelengths have more energy per photon, and hotter stars have a shorter average photon wavelength. An interesting idea would be to have two binary stars of different temperatures (and therefore different average photon wavelength) orbiting each other closely and to have a planet farther away orbiting both stars; this would result in the planet receiving a wider variety of electromagnetic radiation, which would give photosynthetic organisms more options. I don't think that a red dwarf would be a good idea because if the red dwarf is a single star, the habitable zone would be so close that the planet would become tidally locked, and if the red dwarf is a binary star, it would not contribute a significant proportion of light to result in photic diversity (unless the other star is also a red dwarf, in which case we have the same problem as with a single red dwarf).

One problem with brighter stars is that they live shorter. F class (next class after G, which contains the Sun) is probably okay with a lifespan of 2-4 billion years. Any heavier than that, and the timescale is simply too short. Along with frequency, intensity is also important. The Sun emits green light the most, which is why most plants are green. There are still purple bacterial photsynthesizers, though AFAIR the high energy of purple photons can sometimes damage enzymes. https://www.youtube.com/watch?v=IIA-k_bBcL0

Volcanoes will emit sulfur compounds, carbon dioxide, and carbon monoxide into the atmosphere. The sulfur oxides produced with react with the water vapor in the air to produce sulfuric oxyacids, which will be neutralized by the ammonia to form sulfur oxyanions, which will then to to the surface via precipitation.
Formamide will be formed in the atmosphere from ammonia reacting with carbon monoxide and water reacting with hydrogen cyanide, be delivered to the surface via precipitation, and enter the oceans. At the bottom of the oceans, it will be converted by solid acid catalysts or heat from hydrothermal vents back into carbon monoxide and ammonia or into water and hydrogen cyanide. The first two of these compounds are gases at any temperature at which water is not solid (at least at standard pressure) and can only be dissolved in water in limited quantities, so they will reenter the atmosphere. The water will reenter the atmosphere through evaporation. Hydrogen cyanide would be liquid at the temperatures in most of Earth's ocean water, and it is miscible with water, but its vapor pressure is much higher than that of water, so it will evaporate into the atmosphere at a much greater rate that that of water. There will also be a reversible reaction where water and isocyanic acid interchange with ammonia and carbon dioxide. Isocyanic acid will be a similar case to hydrogen cyanide in the sense that its boiling point is near room temperature, and its vapor pressure is much higher than that of water (which is related to its lower boiling point), so it will enter the atmosphere from the oceans much more readily than water.

Wow! Thanks for going through this in so much detail! We should figure out methane and ethane too. Can they be used for respiration after oxygen comes?
Edit:

Edit: I'm considering reducing the percent dinitrogen to forty and scaling some other components up in order to compensate. Is that okay?

That is okay. What substances' percentages will you scale up?

[MathAndCode]

One problem with brighter stars is that they live shorter. F class (next class after G, which contains the Sun) is probably okay with a lifespan of 2-4 billion years. Any heavier than that, and the timescale is simply too short. Along with frequency, intensity is also important. The Sun emits green light the most, which is why most plants are green. There are still purple bacterial photsynthesizers, though AFAIR the high energy of purple photons can sometimes damage enzymes. https://www.youtube.com/watch?v=IIA-k_bBcL0

I was thinking either F and K or G and K. I suspect that plant-analogs will be able to adapt to be able to safely absorb more and more energy from the suns—although it would take a while. Also, if plants are absorbing too many photons of a particular color, they can simply make less chlorophyll.

Wow! Thanks for going through this in so much detail! We should figure out methane and ethane too. Can they be used for respiration after oxygen comes?

Yes. One example is 2O₂+CH₄→CO₂+2H₂O. Of course, living organisms on that planet would likely stage it similarly to how living organisms on Earth stage the oxidation of glucose. Also, some living organisms on Earth generate methane, so it would likely be replenished on this planet.

[Schiaparelliorbust]

I was thinking either F and K or G and K. I suspect that plant-analogs will be able to adapt to be able to safely absorb more and more energy from the suns—although it would take a while. Also, if plants are absorbing too many photons of a particular color, they can simply make less chlorophyll.

If we're going to have a binary system (which it seems like we will now), I prefer G and K.

Yes. One example is 2O₂+CH₄→CO₂+2H₂O. Of course, living organisms on that planet would likely stage it similarly to how living organisms on Earth stage the oxidation of glucose. Also, some living organisms on Earth generate methane, so it would likely be replenished on this planet.

Since methane is lighter than air, do you think there could be balloon-like creatures on this planet? It could be interesting.

[MathAndCode]

If we're going to have a binary system (which it seems like we will now), I prefer G and K.

Okay; that means that photosynthetic organisms would have somewhat more red and near-infrared light to work with.

Since methane is lighter than air, do you think there could be balloon-like creatures on this planet? It could be interesting.

It's certainly possible, somewhat similarly to how fish have swim bladders, and it would be interesting if that occurred.



Edit: I just thought of something important: We should check what frequencies of light, if any, the major components of the atmosphere will absorb or reflect, as this will influence what wavelengths of light phototrophs can use for energy and what wavelengths of light animals can use for vision.

[Schiaparelliorbust]

Okay; that means that photosynthetic organisms would have somewhat more red and near-infrared light to work with.

How far away from the suns is the planet going to be?

Since methane is lighter than air, do you think there could be balloon-like creatures on this planet? It could be interesting.

It's certainly possible, somewhat similarly to how fish have swim bladders, and it would be interesting if that occurred.

Let's not forget this idea then.

Edit: I just thought of something important: We should check what frequencies of light, if any, the major components of the atmosphere will absorb or reflect, as this will influence what wavelengths of light phototrophs can use for energy and what wavelengths of light animals can use for vision.

We'll do this after you finish your atmospheric changes to allow for the 40% dinitrogen. What should I look up exactly?

[MathAndCode]

How far away from the suns is the planet going to be?

As the planet gets farther away from the sun(s), the light energy from the sun(s) will spread out more before reaching the planet, so the planet will get less light energy. Specifically, the amount of light energy that the planet receives will be inversely proportional to the square of its distance from the sun(s). (In our case of the planet orbiting a pair of binary stars, we don't have to worry so much about accounting for the fact that most of the time, one star will be closer to the planet than the other because the distance between the two stars must be relatively small compared to the distance between the stars and the planet anyway in order for the planet to have a stable orbit.) If we assume that the G-type star's bolometric magnitude is equal to that of Earth's Sun and that the K-type star's bolometric magnitude is four-ninths of that of Earth's Sun, then the total magnitude of the two stars would be 1.44 times that of Earth's Sun, so in order to receive the same amount of energy as Earth, an Earth-sized planet orbiting this binary star system would need to be sqrt(1.44)=1.2 times as far away from the binary stars as Earth is from the Sun. (This does make some simplifications, such as ignoring the fact that the planet may absorb a different fraction of the light energy at different frequencies and failing to account for dimming when one of the binary stars passes in front of the other, but it's at least approximately correct and conveys the correct concept.) If we want the alien planet to be slightly warmer than Earth, then we should place it a little closer to the binary stars than that, and if we want it to be a little cooler than Earth, then we should place it a little farther from the binary stars than that.
Also, when I was checking yesterday that the binary stars can be far enough apart from each other to not merge and close enough together so that the planet can be far way enough to have a stable orbit without being too far away to have liquid water (and they indeed can), I learned about the concept of a Roche lobe, which is a region around a star in a binary system such that if a star tries to expand past this region, some of its mass will spill into the other star. I'm wondering whether it's possible to squeeze at least a few more million years of evolution time out of the star system by positioning the stars so that when the G-type star starts to expand near the end of its time in the main sequence, some of its mass will be transferred to the K-type star. It's possible that the decreased mass and pressure of the G-type star will cause it to burn through its remaining hydrogen more slowly, increasing the amount of time that life on the planet has to evolve. However, I'm not a stellar physicist, so for all I know, it's possible that the decreased pressure from the outer layers will cause the star to expand into a red giant sooner, that the star's decreased mass will cause its Roche lobe to shrink in a manner that will result in a runaway effect that won't necessarily be beneficial for our purposes, or that the result of the interaction will be dominated by some factor that I don't even know about.

Let's not forget this idea then.

You should be aware that if an animal only has a balloon and no way to steer itself, then it won't be able to find food, and it will be easy prey for any predator with controlled flight unless it has some other defense. However, I think that a flying animal that uses its balloon in order to not have to spend as much energy producing lift would be more practical. Also, since photosynthetic plants need access to sunlight, it's possible that they could take up this strategy. Not being able to steer towards food wouldn't be an issue because plants get their energy from the Sun and store it using chemicals that they can get from the air, and not being able to steer in order to avoid getting eaten shouldn't be an issue because most plants can't move at all. However, this would present difficulties for the plants in terms of not being able to get nutrients from the soil, and reproduction would also be tricky, both because the floating plants would likely be dispersed too far way from each other for effective sharing of gametes and because the young offspring wouldn't be able to float right away. Also, evolution from land plants requires a set of several large changes that must happen together in order for this to work, making it seem unlikely. However, it's feasible that a sea plant dwelling on the ocean surface could evolve a gas-filled sack near its top in order to prevent waves from flipping it photosynthetic side down. As more of its body comes above water, it will likely be less vulnerable to herbivory by marine herbivores, which will likely serve as an evolutionary pressure that would lead its gas sack to become larger and/or contain a lighter mixture of gases. This could eventually reach the point where the plant starts to float. However, because evolution is gradual, this will likely begin with particular large waves launching the plants a few feet in the air and the plants coming back down to the sea surface. Because the plants won't be in the air for more than a minute or so at a time, they could conceivably survive the ordeal, allowing these plants to evolve to be able to tolerable being in the air better instead of every plant launched into the air dying. (The fact that the plants would likely have had to evolve measures to prevent themselves from drying out as a greater proportion of their bodies came above water would also help.) Pressure from aquatic herbivores and being in the air for longer may lead plants to develop the ability to take in all of the chemicals that they need from the air instead of relying on nutrient-absorbing parts below the waterline. Alternatively, maybe the plants will evolve a feedback mechanism to empty their gas sacks somewhat if they're low on some element or nutrient that they have to get from the water and fill their gas sacks back up once they have enough of it. Also, juvenile floating plants could spend the early part of their lives entirely on the ocean surface. Then again, this is pure speculation, so maybe it won't happen at all or stop before the plants spend long durations of time completely airborne.

We'll do this after you finish your atmospheric changes to allow for the 40% dinitrogen. What should I look up exactly?

We should check whether any of the components will absorb or reflect a significant amount of light in the visible or near-infrared portions of the electromagnetic specturm. We already know that dinitrogen, carbon dioxide, and water vapor won't absorb or reflect too much visible light because they are in Earth's atmosphere in significant quantities. However, this alone doesn't tell us that they don't absorb or reflect near-infrared light. I know that liquid water is very good at absorbing near-infrared light (which may be another pressure leading to the evolution of floating plants if they use near-infrared light for photosynthesis), but I don't think that they same is true for water vapor. I also know that carbon dioxide and other greenhouse gases work by absorbing infrared light, but I think that they absorb mid-infrared or far-infrared light and not near-infrared light (although I will check this). I remembered that sulfate aerosols in Earth's atmosphere can reflect sunlight, cooling the Earth, but I'm not sure which wavelengths this applies to, so we should check that (and also, if necessary, how much we can minimize this effect while still keeping sulfur-oxygen compounds in the atmosphere) before potentially cutting sulfur-oxygen compounds from the atmosphere.
Also, here's my proposed atmosphere with 40% dinitrogen:
40% dinitrogen
20% ammonia
17% carbon dioxide
7% sulfur oxides
6% carbon monoxide
3% hydrogen cyanide
2% hydrogen sulfide
1.5% methane
1.1% water vapor
0.6% ethane
0.6% sulfur oxyacids and oxyanions
0.6% isocyanic acid
0.6% trace gases
I didn't perfectly scale up everything else for several reasons (e.g. not wanting to increase the amount of methane and ethane lest the atmosphere explode once dioxygen is introduced), but as always, I'm willing to change the atmosphere in response to others' suggestions.

[Schiaparelliorbust]

How far away from the suns is the planet going to be?

As the planet gets farther away from the sun(s), the light energy from the sun(s) will spread out more before reaching the planet, so the planet will get less light energy. Specifically, the amount of light energy that the planet receives will be inversely proportional to the square of its distance from the sun(s). (In our case of the planet orbiting a pair of binary stars, we don't have to worry so much about accounting for the fact that most of the time, one star will be closer to the planet than the other because the distance between the two stars must be relatively small compared to the distance between the stars and the planet anyway in order for the planet to have a stable orbit.) If we assume that the G-type star's bolometric magnitude is equal to that of Earth's Sun and that the K-type star's bolometric magnitude is four-ninths of that of Earth's Sun, then the total magnitude of the two stars would be 1.44 times that of Earth's Sun, so in order to receive the same amount of energy as Earth, an Earth-sized planet orbiting this binary star system would need to be sqrt(1.44)=1.2 times as far away from the binary stars as Earth is from the Sun. (This does make some simplifications, such as ignoring the fact that the planet may absorb a different fraction of the light energy at different frequencies and failing to account for dimming when one of the binary stars passes in front of the other, but it's at least approximately correct and conveys the correct concept.) If we want the alien planet to be slightly warmer than Earth, then we should place it a little closer to the binary stars than that, and if we want it to be a little cooler than Earth, then we should place it a little farther from the binary stars than that.

Would you like the planet to be slightly warmer or colder? I don't know much about how climate affects early life on a planet, so I would like to know if you have any thoughts on this. Also, we should determine the tilt of the planet. I think I'd like it to be slightly higher than Earth's.

Also, when I was checking yesterday that the binary stars can be far enough apart from each other to not merge and close enough together so that the planet can be far way enough to have a stable orbit without being too far away to have liquid water (and they indeed can), I learned about the concept of a Roche lobe, which is a region around a star in a binary system such that if a star tries to expand past this region, some of its mass will spill into the other star. I'm wondering whether it's possible to squeeze at least a few more million years of evolution time out of the star system by positioning the stars so that when the G-type star starts to expand near the end of its time in the main sequence, some of its mass will be transferred to the K-type star. It's possible that the decreased mass and pressure of the G-type star will cause it to burn through its remaining hydrogen more slowly, increasing the amount of time that life on the planet has to evolve. However, I'm not a stellar physicist, so for all I know, it's possible that the decreased pressure from the outer layers will cause the star to expand into a red giant sooner, that the star's decreased mass will cause its Roche lobe to shrink in a manner that will result in a runaway effect that won't necessarily be beneficial for our purposes, or that the result of the interaction will be dominated by some factor that I don't even know about.

I also don't think that is a good idea. It could destroy the orbit of the planet. It might even cause the heavier star to entirely devour the lighter one, turning it into a brighter star with a shorter lifespan, which certainly isn't good for our purposes

Let's not forget this idea then.

You should be aware that if an animal only has a balloon and no way to steer itself, then it won't be able to find food, and it will be easy prey for any predator with controlled flight unless it has some other defense. However, I think that a flying animal that uses its balloon in order to not have to spend as much energy producing lift would be more practical. Also, since photosynthetic plants need access to sunlight, it's possible that they could take up this strategy. Not being able to steer towards food wouldn't be an issue because plants get their energy from the Sun and store it using chemicals that they can get from the air, and not being able to steer in order to avoid getting eaten shouldn't be an issue because most plants can't move at all. However, this would present difficulties for the plants in terms of not being able to get nutrients from the soil, and reproduction would also be tricky, both because the floating plants would likely be dispersed too far way from each other for effective sharing of gametes and because the young offspring wouldn't be able to float right away. Also, evolution from land plants requires a set of several large changes that must happen together in order for this to work, making it seem unlikely. However, it's feasible that a sea plant dwelling on the ocean surface could evolve a gas-filled sack near its top in order to prevent waves from flipping it photosynthetic side down. As more of its body comes above water, it will likely be less vulnerable to herbivory by marine herbivores, which will likely serve as an evolutionary pressure that would lead its gas sack to become larger and/or contain a lighter mixture of gases. This could eventually reach the point where the plant starts to float. However, because evolution is gradual, this will likely begin with particular large waves launching the plants a few feet in the air and the plants coming back down to the sea surface. Because the plants won't be in the air for more than a minute or so at a time, they could conceivably survive the ordeal, allowing these plants to evolve to be able to tolerable being in the air better instead of every plant launched into the air dying. (The fact that the plants would likely have had to evolve measures to prevent themselves from drying out as a greater proportion of their bodies came above water would also help.) Pressure from aquatic herbivores and being in the air for longer may lead plants to develop the ability to take in all of the chemicals that they need from the air instead of relying on nutrient-absorbing parts below the waterline. Alternatively, maybe the plants will evolve a feedback mechanism to empty their gas sacks somewhat if they're low on some element or nutrient that they have to get from the water and fill their gas sacks back up once they have enough of it. Also, juvenile floating plants could spend the early part of their lives entirely on the ocean surface. Then again, this is pure speculation, so maybe it won't happen at all or stop before the plants spend long durations of time completely airborne.

Perhaps they can have air sacks during their sporal stage? It could be useful in places with not as much wind, but elsewhere it might not provide much of an advantage. Maybe we could even have inflatable plants? In times of danger or drought or some other hardship, they could deflate themselves, and when everything back to normal they could inflate themselves. It could allow for higher-reaching plants without too much support structure, because the air is literally holding them up.

We'll do this after you finish your atmospheric changes to allow for the 40% dinitrogen. What should I look up exactly?

We should check whether any of the components will absorb or reflect a significant amount of light in the visible or near-infrared portions of the electromagnetic specturm. We already know that dinitrogen, carbon dioxide, and water vapor won't absorb or reflect too much visible light because they are in Earth's atmosphere in significant quantities. However, this alone doesn't tell us that they don't absorb or reflect near-infrared light. I know that liquid water is very good at absorbing near-infrared light (which may be another pressure leading to the evolution of floating plants if they use near-infrared light for photosynthesis), but I don't think that they same is true for water vapor. I also know that carbon dioxide and other greenhouse gases work by absorbing infrared light, but I think that they absorb mid-infrared or far-infrared light and not near-infrared light (although I will check this). I remembered that sulfate aerosols in Earth's atmosphere can reflect sunlight, cooling the Earth, but I'm not sure which wavelengths this applies to, so we should check that (and also, if necessary, how much we can minimize this effect while still keeping sulfur-oxygen compounds in the atmosphere) before potentially cutting sulfur-oxygen compounds from the atmosphere.
Also, here's my proposed atmosphere with 40% dinitrogen:
40% dinitrogen
20% ammonia
17% carbon dioxide
7% sulfur oxides
6% carbon monoxide
3% hydrogen cyanide
2% hydrogen sulfide
1.5% methane
1.1% water vapor
0.6% ethane
0.6% sulfur oxyacids and oxyanions
0.6% isocyanic acid
0.6% trace gases
I didn't perfectly scale up everything else for several reasons (e.g. not wanting to increase the amount of methane and ethane lest the atmosphere explode once dioxygen is introduced), but as always, I'm willing to change the atmosphere in response to others' suggestions.

Since there is a slightly cooler star along with another one similar to the Sun, the would probably be more infrared light coming from the suns, so it might stunt plant growth if we put too many infrared absorbing compounds into the atmosphere.

[MathAndCode]

Would you like the planet to be slightly warmer or colder? I don't know much about how climate affects early life on a planet, so I would like to know if you have any thoughts on this. Also, we should determine the tilt of the planet. I think I'd like it to be slightly higher than Earth's.

I figure that a slightly warmer planet/more solar energy would be better for life because it would have more energy to work with. Also, I figured that reduced seasonal variation would likely make things easier for life, but I could be wrong. Additionally, I would like like the planet ot have large tides in order to make the transition from sea to land more gradual and therefore easier, like in Biblaridion's series.

I also don't think that is a good idea. It could destroy the orbit of the planet.

I don't think that that would happen because the total mass would be unaffected.

It might even cause the heavier star to entirely devour the lighter one, turning it into a brighter star with a shorter lifespan, which certainly isn't good for our purposes.

I was only proposing it because I figured that it was possible to make the opposite occur, but I shall trust your stellar physics knowledge and abandon that idea.

Since there is a slightly cooler star along with another one similar to the Sun, the would probably be more infrared light coming from the suns, so it might stunt plant growth if we put too many infrared absorbing compounds into the atmosphere.

Compounds that absorb mid- or far-infrared light should be okay because they don't carry nearly as much energy per photon, and most of the suns' energy won't be in that range. A G-type main sequence star's photon output is centered in the green wavelengths, and a K-type main sequence star's photon output is centered in the red wavelengths. Carbon dioxide and methane don't have major absorption/scattering peaks until about 1,900 nm and 2,200 nm respectively; this is out of near-infrared, and 1,900 nm wavelength carries less than 40% energy per photon as the least energetic part of the visible spectrum. On the other hand, water vapor starts absorbing significant fractions of the light in the near-infrared range, but because we can't simply remove water from our planet (at least if we want a biosphere), we'll probably have to make the cooler star hot-end K or even cool-end G. It's a good thing that we checked this.

[Schiaparelliorbust]

I figure that a slightly warmer planet/more solar energy would be better for life because it would have more energy to work with. Also, I figured that reduced seasonal variation would likely make things easier for life, but I could be wrong. Additionally, I would like like the planet ot have large tides in order to make the transition from sea to land more gradual and therefore easier, like in Biblaridion's series.

Yeah, I just realized that we don't have a moon. Should we make it 50% heavier than ours? If you'd like the tilt to be lower, then can we make the variation of the tilt larger?

I don't think that that would happen because the total mass would be unaffected.

Yeah. The distance would also probably be very small compared to the distance between the star and the planet.

I was only proposing it because I figured that it was possible to make the opposite occur, but I shall trust your stellar physics knowledge and abandon that idea.

I assumed that the larger one would have more influence. Is the opposite of what I said possible?

Compounds that absorb mid- or far-infrared light should be okay because they don't carry nearly as much energy per photon, and most of the suns' energy won't be in that range. A G-type main sequence star's photon output is centered in the green wavelengths, and a K-type main sequence star's photon output is centered in the red wavelengths. Carbon dioxide and methane don't have major absorption/scattering peaks until about 1,900 nm and 2,200 nm respectively; this is out of near-infrared, and 1,900 nm wavelength carries less than 40% energy per photon as the least energetic part of the visible spectrum. On the other hand, water vapor starts absorbing significant fractions of the light in the near-infrared range, but because we can't simply remove water from our planet (at least if we want a biosphere), we'll probably have to make the cooler star hot-end K or even cool-end G. It's a good thing that we checked this.

Wikipedia says that a K-type star has masses between 0.5 and 0.8 Solar masses and surface temperature between 3,900 and 5,200 K. 5200K emits 705.71 nm light the most, which is on the somewhat far red end of the visible spectrum.

[MathAndCode]

Yeah, I just realized that we don't have a moon. Should we make it 50% heavier than ours?

Yes. Let's stick with the values in Biblaridion's series.

If you'd like the tilt to be lower, then can we make the variation of the tilt larger?

Again, I'm concerned that this might hinder life. If you think that large seasons will be okay, we have have those, and if you think that variations in tilt will be okay, we can have that, but we need to make sure that they won't hinder life first.

I assumed that the larger one would have more influence. Is the opposite of what I said possible?

My idea was that smaller stars don't become red giants as quickly, but then again, I'm not a stellar physicist, so I shall trust you.

Wikipedia says that a K-type star has masses between 0.5 and 0.8 Solar masses and surface temperature between 3,900 and 5,200 K. 5200K emits 705.71 nm light the most, which is on the somewhat far red end of the visible spectrum.

And most of the light is going to be centered around that, so it will emit a bunch of light in the near-infrared but not much light in the mid-infrared or far-infrared.

[Schiaparelliorbust]

Yeah, I just realized that we don't have a moon. Should we make it 50% heavier than ours?

Yes. Let's stick with the values in Biblaridion's series.

I totally forgot the values there. They were (not so coincidentally) the same. Should the distance also be the same?

Again, I'm concerned that this might hinder life. If you think that large seasons will be okay, we have have those, and if you think that variations in tilt will be okay, we can have that, but we need to make sure that they won't hinder life first.

Ok then, let's make the values similar to that of Earth's but for when life emerges onto land, the supercontinent will extend from (both) pole(s) to the equator for climactic variation.

I assumed that the larger one would have more influence. Is the opposite of what I said possible?

My idea was that smaller stars don't become red giants as quickly, but then again, I'm not a stellar physicist, so I shall trust you.

I'm no stellar physicist either, so I think we should avoid taking too many risks.

And most of the light is going to be centered around that, so it will emit a bunch of light in the near-infrared but not much light in the mid-infrared or far-infrared.

So if I understand correctly there will be spikes at near-infrared and green. Should the G-type star be slightly heavier or lighter than the Sun? We don't have too much wiggle room, but it could make a difference (0.84 to 1.15 solar masses) (5,300 and 6,000 K).

[MathAndCode]

I totally forgot the values there. They were (not so coincidentally) the same. Should the distance also be the same?

Yes; I have no objection with that.

Ok then, let's make the values similar to that of Earth's but for when life emerges onto land, the supercontinent will extend from (both) pole(s) to the equator for climactic variation.

Yes, that sounds good.

So if I understand correctly there will be spikes at near-infrared and green. Should the G-type star be slightly heavier or lighter than the Sun? We don't have too much wiggle room, but it could make a difference (0.84 to 1.15 solar masses) (5,300 and 6,000 K).

I think that we should make the K-type star hot enough to spike at red because water vapor will absorb a bunch of the infrared light. We may even end up making it cool-end G.

[Schiaparelliorbust]

I think that we should make the K-type star hot enough to spike at red because water vapor will absorb a bunch of the infrared light. We may even end up making it cool-end G.

Isn't near infrared already red? Or is this a lot of infrared light that is being absorbed too?

[MathAndCode]

Isn't near infrared already red? Or is this a lot of infrared light that is being absorbed too?

Near-infrared is the part of the infrared spectrum that is closest to visible portion of the electromagnetic spectrum.

[Schiaparelliorbust]

Near-infrared is the part of the infrared spectrum that is closest to visible portion of the electromagnetic spectrum.

Oh, ok. Are we done with the stars or are we still trying to have less infrared light?

[MathAndCode]

Oh, ok. Are we done with the stars or are we still trying to have less infrared light?

Let's be done with the stars.

[Schiaparelliorbust]

Let's be done with the stars.

Could you then give the masses and peak-frequency of both stars? I would like to get started with the photosynthesizers.

[MathAndCode]

Could you then give the masses and peak-frequency of both stars? I would like to get started with the photosynthesizers.

Let's have the primary star be the same as the Sun (peaking in the green) and the smaller star be on the G-K boundary (four-fifths the mass of the Sun and peaking in the red).

[Schiaparelliorbust]

Let's have the primary star be the same as the Sun (peaking in the green) and the smaller star be on the G-K boundary (four-fifths the mass of the Sun and peaking in the red).

Since green light has higher energy would green photosynthesizers be the dominant group or would it depend more on which color evolves first? I also just watched Artifexian's video on sky and plant color, and he said three things which I think are very relevant:
1)The sky can change color periodically in a binary star system like ours due to eclipsing. We should probably figure out how long it takes for the stars to orbit each other.
2)Plants might evolve to either have the color of the most abundant wavelength or to have the complement color of it. In the first case, the plants would do this to avoid the harmful radiation of the most abundant frequency and absorb everything else. They would probably do this if the most abundant frequency is a very high frequency, like blue or violet. In the second case, they would so this to take in the most abundant frequency. They would probably do this in the opposite case, where the most abundant frequency is lower frequency like yellow or red. If it's really low frequency, they might become black to absorb all that they can.
3) A thicker atmosphere means a redder sky due to more Rayleigh scattering. In the video description, there is a spreadsheet to help calculate the color of an atmosphere. The spreadsheet also links to another spreadsheet that can calculate atmospheric pressure and density more accurately based on different gases, gravity and escape velocity (I don't know why we would need that last one though).

[HelicopterCat3]

Let's have the primary star be the same as the Sun (peaking in the green) and the smaller star be on the G-K boundary (four-fifths the mass of the Sun and peaking in the red).

Since green light has higher energy would green photosynthesizers be the dominant group or would it depend more on which color evolves first? I also just watched Artifexian's video on sky and plant color, and he said three things which I think are very relevant:
1)The sky can change color periodically in a binary star system like ours due to eclipsing. We should probably figure out how long it takes for the stars to orbit each other.
2)Plants might evolve to either have the color of the most abundant wavelength or to have the complement color of it. In the first case, the plants would do this to avoid the harmful radiation of the most abundant frequency and absorb everything else. They would probably do this if the most abundant frequency is a very high frequency, like blue or violet. In the second case, they would so this to take in the most abundant frequency. They would probably do this in the opposite case, where the most abundant frequency is lower frequency like yellow or red. If it's really low frequency, they might become black to absorb all that they can.
3) A thicker atmosphere means a redder sky due to more Rayleigh scattering. In the video description, there is a spreadsheet to help calculate the color of an atmosphere. The spreadsheet also links to another spreadsheet that can calculate atmospheric pressure and density more accurately based on different gases, gravity and escape velocity (I don't know why we would need that last one though).

Well green light is not necessarily the most abundant in energy. All visible light has essentially (besides red and purple which are on the far ends of the spectrum) the same energy level. Plants could evolve to be yellow and absorb yellow light or could be blue, orange, etc. It all depends on what wavelength of light is transmitted the most from the star. It happened that our star, the Sun, have of green light the most, so photosynthetic organisms found they were able to get more energy out of it and evolved to have chloroplasts. Purple or reddish plants on this planet usually don't get a lot of sunlight which is why they absorb the colors that are less bountiful but are still there. Also, the atmosphere of this proposed planet has varies in its gas content more than our planet so the gases could prevent some colors from showing through, giving the planet's surface a different hue (which would actually be really cool to experience).
Surprisingly, a lot of a planet's life relies on the energy given by its star. So really, we should decide what kinda of star this planet gets first.

[Schiaparelliorbust]

Well green light is not necessarily the most abundant in energy. All visible light has essentially (besides red and purple which are on the far ends of the spectrum) the same energy level. Plants could evolve to be yellow and absorb yellow light or could be blue, orange, etc. It all depends on what wavelength of light is transmitted the most from the star. It happened that our star, the Sun, have of green light the most, so photosynthetic organisms found they were able to get more energy out of it and evolved to have chloroplasts. Purple or reddish plants on this planet usually don't get a lot of sunlight which is why they absorb the colors that are less bountiful but are still there. Also, the atmosphere of this proposed planet has varies in its gas content more than our planet so the gases could prevent some colors from showing through, giving the planet's surface a different hue (which would actually be really cool to experience).

Chlorophyll reflects green light, so plants don't really use any of it at all. Magenta plants would use it though.

Surprisingly, a lot of a planet's life relies on the energy given by its star. So really, we should decide what kinda of star this planet gets first.

We already decided on having a binary system: one star will have about the same mass as the sun, while the other one will be a bit lighter.

[MathAndCode]

Since green light has higher energy would green photosynthesizers be the dominant group or would it depend more on which color evolves first?

Chlorophyll-containing plants on Earth have two different photosystems that have different absorption peaks and drive different immediate reactions. Plants on our alien planet would likely do something similar.

[Schiaparelliorbust]

Chlorophyll-containing plants on Earth have two different photosystems that have different absorption peaks and drive different immediate reactions. Plants on our alien planet would likely do something similar.

I found this very relevant thread on Reddit about alternatives to chlorophyll. Maybe it could be of help?

[Schiaparelliorbust]

Before we do other stuff, I think we should determine the day length and direction of rotation (prograde/retrograde). I also got GPlates to simulate continental drift. I'm still learning how to use it though. Sorry about the double post.

[MathAndCode]

Before we do other stuff, I think we should determine the day length and direction of rotation (prograde/retrograde).

The direction of rotation shouldn't matter much, so let's use prograde because that's more realistic. As for day length, I see no reason to depart from the day length used in Biblaridion's series (which I believe is twenty hours).