What kind of star would allow for red plant life?

Question

I'm designing an alien world in which plantlife is mostly red. I've read that the type of star the planet orbits plays an important role to the plants' color (For example, worlds around M type stars are more likely to have black plants to absord more sunlight). My world is pretty similar to Earth in terms of gravity, atmosphere and chemical composition. So what kind of star do i need to use to for red plant life to be dominant?

Answer 1

To continue from my last post on this subject, if you want red plants, then you probably want to have a star that emits plenty of light in shorter wavelengths. If most of the emitted energy is red or near-IR, then you want to be absorbing that light and not reflecting it, which means you probably won't be reddish (or near-IR colored, which complex life in such an environment is likely to be able to distinguish).

Plants aren't often red-colored on Earth, because using chlorophyll is pretty popular and chlorophyll absorbs blue and red light, reflecting the unused green. That doesn't have to be the case, though. Have a look at this graph of the absorption spectra of some terrestrial photosynthetic pigments:

(original source at plantphys.info no longer exists, haven't found a new source)

There already exist a number of photosynthetic pigments and accessory pigments that don't absorb red light, and give us things that are carrot-orange and tomato-red. All you have to do is to handwave in either a) the absence of chlorophyll (and all its relatives like bacteriochlorophyll) or b) the existence of an alternative dominant photopigment that's approximately as efficient and effective as chlorophyll, ensuring that even if green stuff does exist, most stuff isn't green. The space of chemicals that could absorb a photon and cough up an electron is vast, and by no means thoroughly explored by either nature or science. You have free rein to just make something up, and it'll be plausible enough, which is nice.

Then all you need to do is to provide plenty of blue, green and yellow light.

Here we have the emission spectra of black bodies of temperatures corresponding to a G2V star (such as the Sun), a K2V star (such as Epsilon Eridani) and an M0V star (such as Lacaille 8760, though that star's a bit hotter and brighter than the example in the chart)

The area under the graph is roughly equivalent to the proportion of the energy radiated from the star. You can see that the Sunlike star emits lots of energy all across the visible spectrum (which is crudely marked, and corresponds to the 380nm to 780nm band), but the M0V red dwarf emits lots of red and IR, but not nearly so much shorter wavelength stuff.

I'd say that anything between a moderately warm K-class orange star, and a G-class (or maybe a cool F-class) star should give you all the short wavelength light you need for red-reflecting photosynthesizers to do just fine.