Atmosphere color of carbon planets

[kikinho]

Hi. I've read much about carbon planets. I read that hot carbon planets might have much CO in the air and that colder planets like Earth or Titan the air may be rich in methane and nitrogen, like Titan.

I'm making a system in which planets, moons are mostly made of carbon compounds. The planet I'm making is as hot as Earth and have atmosphere made of the following gases:

Nitrogen: 65%
Methane: 33%
Carbon monoxyde: 1%
Other gases: 1%

The air pressure is 13atm. The planet is illuminated by two close M0V dwarf stars.

The image below is what might look like a methane rich atmosphere at 13atm. Note: I still didn't make the clouds.



What I want to know now is... For a methane rich atmosphere at 13atm, the color of the air in the picture is correct? I'm doing this question because I read that methane gas is blue. But in this case, do you think that the blue should be brighter? Or the sky should be more Earth-like? Or even more dark blue? I simply don't know.

One more simple question. What would be the color of a planet rich in CO gas in the air?

If possible, could someone post a picture of what might look like a methane rich air?

[kikinho]

So many views and no answers?

I need an answer. I only want to know if a methane atmosphere would look like the image of that sky I posted and the color of an atmosphere rich in CO.

[buggs_moran]

Keep in mind that many of the members here are probably celebrating the holidays.

If you haven't already, you might read through this thread

http://www.bautforum.com/archive/index.php/t-60031.html

over at Bad Astronomy. You'll notice many of the same user names as here... I personally don't know much about atmospheres, but did some quick searching. I would imagine that the color would be heavily influenced by the temperature and particulate matter in the atmosphere... The thread has a bunch of links as well...

[eburacum45]

Actually, in a book I have by the veteran space artist David Hardy, he says that methane is very slightly green in large amounts. But Rayleigh scattering would still apply; this too would tend to turn the atmosphere greenish at 13 atmospheres. So a blue green tint seems likely.

However on a carbon planet, I would guess that hydrocarbon particulates would have a strong effect on the colour- turning the clouds, and probably the ground too, orange or brownish. Think of Titan, where the colours orange and brown seem to predominate. This world has methane and organic compounds, and so (I think) would a carbon world. Imagine crude oil sprayed into the air and onto the ground; the nice blue-green colour of a pure atmosphere would (I think) be lost.

[kikinho]

My carbon planet has a methane rich atmosphere, but the amount of hydrocarbons are very small in the air, since my double M dwarf stars are not flare variable stars, but stable ones. The high atmosphere has a certain amount of noble gases that protect the surface from the weak ultraviolet emmited by the star.

Some planets in my system are big rocky and massive enough to retain helium in average amounts. The are also some nean in the stratosphere with helium. The troposphere is mostly made of nitrogen and methane with clouds of water/ammonia.
Few hydrocarbon and CO are present in the air. The amount of these substances are slightly higher in concentration than the CO2 in our atmosphere.

The atmosphere pressure is 17atm, so I think the sky will be dark green with green to orange clouds.

This is a big rocky planet with radius of 13783km and gravity about 17.5 m/s??. This planet also have a magnetic field that is many times stronger than that of Earth. So this planet is even more protected from high radiation came from outer space and the stars than Earth. This planet also possesses one big moon and some small ones. Have a dark thin ring.
This planet is made mostly of carbon, but is also very rich in many kinds of metals, from the core to the surface. Most volatiles are present in the mantle and the surface has much more land than liquid.

Some other planets in this system are similar with such planet.

[kikinho]

I'll show what a methane atmosphere may look like:

Thick air:


Thick air sunset:


Thin air:


Thin air sunset:


Thick air rich in methane, CO with sulfur clouds.


What do you think?

[Tuefish]

The thick atmospheres look a bit too saturated, I think (if you will have a thick atmosphere) that you should desaturate it a bit to a grey-ish tint, the thin atmospheres look much more realistic. And remember, the color of the suns has a big effect on the color of the atmosphere.
(I think)